Introduction: Why Useful Digital Products Do Not Always Make Money
A developer builds a useful application. A creator publishes excellent educational videos. A business owner launches an online store. A consultant develops a service that saves customers hours of work.
Each has created something potentially valuable.
Yet the developer may struggle to find paying users. The creator may attract an audience but earn little revenue. The online store may generate sales without making a profit. The consultant may deliver excellent work but charge too little to cover the time involved.
What explains the difference?
The answer lies in the relationship between value creation, value delivery, and value capture.
These are three connected but distinct parts of economic activity.
- Value creation means producing a benefit that someone needs or wants.
- Value delivery means getting that benefit to the intended customer in a usable and reliable form.
- Value capture means retaining an appropriate portion of the economic value through revenue, savings, ownership, or another measurable benefit.
A business can succeed at one and fail at another.
An excellent product with no effective distribution may remain undiscovered. A popular service with excessive operating costs may lose money. A profitable business may still be vulnerable if another company controls its customer relationships, distribution or essential infrastructure.
Understanding these relationships gives you a practical framework for evaluating digital businesses, building products, choosing business models and identifying opportunities in the digital economy.
This chapter develops that framework from the perspective of an individual creator, a small business and a digital platform.
1. Understand the Three Stages of Digital Economic Value
Consider a developer who builds an online appointment-booking system for small clinics.
The system reduces the time staff spend answering calls, organizing appointments and notifying patients.
That benefit is the starting point, but it is not the entire business.
Stage 1: Create value
The developer identifies a real problem and builds a solution.
The solution may help the clinic:
- Reduce administrative work.
- Organize appointments more accurately.
- Reduce missed appointments through reminders.
- Improve the patient booking experience.
- Free staff to perform other important tasks.
The product creates value if the benefits are meaningful to the clinic and its patients.
Stage 2: Deliver value
The developer must make the solution accessible and usable.
This could involve a mobile-friendly interface, staff training, reliable hosting, technical support, data protection, payment arrangements and integration with the clinic's existing workflow.
A product that works only under ideal conditions may fail to deliver its promised value in everyday use.
Stage 3: Capture value
The developer needs a sustainable way to benefit economically from providing the solution.
Possible arrangements include:
- A one-time installation fee.
- A monthly subscription.
- A maintenance contract.
- A per-location licence.
- A fee for additional features.
- A combination of setup and recurring service charges.
The right arrangement depends on customer needs, the costs of delivering the service, alternatives in the market and the value customers recognize.
The relationship can be summarized as:
PROBLEM → SOLUTION → DELIVERY → CUSTOMER BENEFIT → REVENUE → SUSTAINABLE OPERATIONS
Each stage must work well enough for the business to survive.
2. Start With the Customer's Economic Problem
Many digital products begin with a technology question:
“What can I build with AI?”
“What application should I develop?”
“What digital product is trending?”
These questions can inspire experimentation, but they do not establish that a viable business opportunity exists.
A stronger starting point is:
Who experiences a problem, what does that problem cost them, and how could a solution improve their situation?
Problems have different economic consequences.
A business may lose money because of wasted materials, missed sales, fraud, inefficient processes, unreliable information or excessive administrative work.
An individual may spend too much time searching for reliable information, learning a skill, organizing work or completing repetitive tasks.
A solution can create value by increasing revenue, reducing costs, protecting assets, saving time, improving quality or making an important activity possible.
Example: A small printing business
Imagine a printing business that receives orders through calls, messages and social media.
Customers frequently request quotations, ask about delivery dates, send files in different formats and follow up on unfinished orders.
The business owner spends hours coordinating these requests.
A digital solution might provide:
- A structured order form.
- A catalogue of printing services.
- Clear specifications and pricing rules.
- File-upload instructions.
- Order-status tracking.
- Automated customer notifications.
- A record of deposits, balances and completed jobs.
The opportunity is not simply to build a website.
It is to reduce the friction involved in ordering printing services and managing the work.
The website or application is the delivery mechanism. The economic value comes from solving the underlying problem.
A practical problem statement
Before building a product, complete this sentence:
“My intended customer is ______. They struggle with ______. This causes ______. My proposed solution will help them ______. I will test whether the improvement is valuable enough for them to ______.”
The final blank might mean pay, adopt the solution, recommend it or change an existing process.
Do not assume that a problem is commercially important merely because you can describe it clearly.
Talk to potential customers, observe their current workflow and test whether the proposed improvement matters to them.
3. Distinguish Value From Revenue
Revenue is the money a business receives from selling goods or services. It is not a complete measure of the value created, and it is not the same as profit.
Imagine that a digital service helps a customer save the equivalent of ₦100,000 in avoidable costs over a year.
The service charges ₦25,000 for that year.
If the savings are real and the comparison is fair, the customer may receive an economic benefit of approximately ₦75,000 before considering other costs or effects.
The provider receives ₦25,000 in revenue, but the customer's benefit is not limited to that payment.
This example illustrates an important principle: a useful product can create more value for a customer than the amount the provider charges.
However, the figures are hypothetical. Real savings must be measured against a credible baseline, and the customer must account for implementation costs, training, disruption and other effects.
Value has several dimensions
A digital product can create value by:
Saving money: reducing unnecessary expenditure, transaction costs or losses.
Saving time: reducing repetitive tasks, delays or search effort.
Increasing revenue: helping customers reach buyers, convert enquiries or serve more customers.
Reducing risk: preventing errors, improving security or making operations more reliable.
Improving quality: helping people make better decisions or produce more consistent work.
Expanding access: enabling people to obtain services that were previously difficult to reach.
Creating new capabilities: allowing customers to perform tasks that were previously too expensive or technically difficult.
Not every benefit is immediately measurable in money. Some benefits, such as convenience, accessibility or confidence, may still influence purchasing decisions.
The challenge is to understand which benefits matter most to the intended customer and how to demonstrate them honestly.
4. Understand How Digital Businesses Capture Value
After identifying a valuable problem and delivering a useful solution, a business needs an appropriate economic model.
A business model explains how an organization creates and delivers value and how it sustains itself economically.
The revenue model is one component of that larger system.
One-time sales
A customer pays once for a product or a defined service.
Examples include a website project, an ebook, a design template or a software licence with a specified purchase arrangement.
This model can be straightforward, but the business must continue finding customers or sell additional products unless the arrangement includes recurring payments.
Subscriptions
Customers pay at regular intervals for continued access or service.
Examples include cloud software, membership communities, online learning platforms and business tools.
Subscriptions can make revenue more predictable, but only when customers continue to see enough value to justify renewal.
The business must also budget for ongoing hosting, maintenance, support, product development and customer acquisition.
Advertising
A publisher or platform may earn revenue by displaying advertisements.
The publisher typically needs to attract an audience that advertisers value and comply with the advertising provider's requirements.
Large traffic numbers alone do not guarantee strong earnings. Audience characteristics, geography, content suitability, advertiser demand, engagement and other factors can influence revenue.
Affiliate commissions
A publisher or creator recommends a product or service and receives a commission when qualifying actions occur under an affiliate agreement.
The model depends on relevant recommendations, customer trust, merchant terms and successful conversions.
Commissions are not guaranteed, and programs can change their terms.
Transaction fees
A platform charges a fee when it facilitates a transaction between participants.
Examples include certain marketplaces, booking services and payment-related platforms.
The business must ensure that the fee is justified by the service provided and that it can attract enough transactions to cover its costs.
Professional services
A business sells expertise, implementation, maintenance, consulting or other services.
This can be attractive to a skilled developer, designer, marketer or technology consultant because customers are paying for an outcome rather than simply accessing a product.
However, a service business can become constrained by the time and capacity of the people delivering the work.
Freemium
A product offers a free version alongside paid features or higher usage limits.
The free version may help people discover the product. Some users may later pay for additional capabilities.
The business must still pay for the resources used by free customers and establish a realistic path to sustainable revenue.
Choosing the model
Do not select a revenue model solely because it is popular.
Ask:
- What does the customer expect to receive?
- How often does the customer receive value?
- Is the benefit recurring or one-time?
- Who pays, and what triggers payment?
- What does delivery cost?
- What level of support is required?
- Can the model remain sustainable as usage increases?
- Are the terms understandable and fair?
A good business model connects the payment arrangement to the value delivered without making the economics unnecessarily complicated.
5. Follow the Money: Revenue Is Not Profit
One of the most important mistakes in digital entrepreneurship is treating sales as evidence of financial success.
A business can generate revenue and still lose money.
Consider a hypothetical digital service with the following monthly figures.
| Item | Amount |
|---|---|
| Revenue | ₦500,000 |
| Direct delivery costs | ₦150,000 |
| Customer acquisition and marketing | ₦100,000 |
| Software, hosting and administration | ₦80,000 |
| Other operating expenses | ₦70,000 |
| Remaining amount before tax and unlisted costs | ₦100,000 |
The business receives ₦500,000 but has only ₦100,000 remaining under these assumptions.
The figures are illustrative, not a forecast or a claim about typical Nigerian business costs.
The example shows why revenue alone tells an incomplete story.
Understand the main financial measures
Revenue: money earned from selling products or services, subject to the accounting treatment used.
Direct costs: costs directly associated with delivering the product or service, such as materials, transaction charges or subcontracted production.
Gross profit: revenue minus the direct costs included in the relevant gross-profit calculation.
Operating expenses: costs of running the business, such as administration, marketing, software and other overheads.
Net profit: the amount remaining after the relevant expenses, interest, taxes and other applicable items are accounted for.
Cash flow: the movement of money into and out of the business. Cash flow can differ from accounting profit because of payment timing, unpaid invoices, equipment purchases, loans and other factors.
A business may appear profitable on paper while struggling to pay bills because customers have not paid their invoices.
A simple contribution calculation
Suppose a digital product sells for ₦10,000 and its variable costs are ₦3,000 per sale.
The contribution before fixed costs is:
₦10,000 − ₦3,000 = ₦7,000 per sale.
If monthly fixed costs are ₦140,000, then the simplified break-even volume is:
₦140,000 ÷ ₦7,000 = 20 sales.
This assumes that the selling price and variable cost remain constant, all sales are collected, and there are no additional relevant costs omitted from the calculation.
Actual break-even analysis must account for the business's real cost structure.
The lesson is simple: understand the economics of each sale before assuming that more sales will solve the problem.
6. Understand Distribution: A Valuable Product Must Reach Its Customers
Distribution is the process through which a product or service reaches the people who need it.
In the digital economy, distribution can involve search engines, websites, app stores, social platforms, email lists, online marketplaces, partnerships, direct sales and professional networks.
A product can be excellent but commercially unsuccessful if potential customers cannot discover it or access it easily.
Example: Two educational products
Imagine two creators who produce equally useful learning materials.
Creator A publishes the material on a website but has no clear audience, distribution plan or way to help readers discover it.
Creator B identifies the audience, publishes useful search-focused content, distributes excerpts through relevant channels, builds a permission-based email list and directs interested readers to the complete material.
Creator B has developed a more deliberate distribution system.
That does not guarantee success. Competition, product quality, pricing, trust and other factors still matter. But the product has a clearer path to its intended users.
Distribution channels have different trade-offs
Search engines: can connect people with content or services when they actively seek a solution. Visibility depends on relevance, competition, technical quality and other factors.
Social platforms: can help content reach audiences, but distribution depends partly on platform policies, algorithms and account access.
Email: can support direct communication with people who have agreed to receive messages. It requires responsible list management and compliance with applicable rules.
Marketplaces: can provide access to existing buyers, but sellers may face fees, competition, platform restrictions and limited control over the customer relationship.
Direct sales: can work well for business services and higher-value solutions, although finding and converting customers takes time and effort.
Partnerships: can help a business reach relevant customers through organizations that already have trusted relationships with them.
The best distribution strategy depends on the product, customer, budget and buying process.
Do not confuse rented reach with owned relationships
A social-media following can be useful, but the platform controls many of the rules governing access to that audience.
An email list, customer database or direct relationship may offer different forms of control, although each requires proper security, consent and maintenance.
A resilient business avoids depending entirely on one channel when practical alternatives exist.
7. Understand Network Effects and Platform Power
Some digital products become more useful as additional people or organizations join them.
This is known as a network effect.
Direct network effects
A communication service may become more useful when more of the people you want to contact use it.
The additional participants increase the usefulness of the same service to existing users.
Indirect network effects
A marketplace may become more useful to buyers when more relevant sellers join. More buyers can, in turn, attract additional sellers.
The value increases through interaction between different participant groups.
Why network effects matter economically
Strong network effects can help a platform attract users, retain participants and establish a competitive position.
However, network effects do not automatically guarantee that a company will dominate a market or remain successful. Poor service, competition, regulation, changes in technology and other factors can weaken a platform's position.
Network effects can also create problems.
A powerful platform may gain significant influence over how customers discover products, how sellers reach buyers, what fees participants pay and which information receives visibility.
This can make it difficult for businesses to operate independently of the platform.
A practical example
Imagine a marketplace for local printing services.
More reliable printing businesses can attract more customers. More customers can make the marketplace more attractive to printers.
But the platform must solve both sides of the problem.
Customers need accurate listings, credible reviews, transparent prices, dependable fulfilment and a workable dispute process.
Printers need relevant enquiries, fair terms, timely payments and a reasonable cost of acquiring customers through the platform.
If either group receives too little value, participation may decline.
A marketplace's real economic strength depends on the quality of these interactions, not simply the number of registered accounts.
8. Understand Data as an Economic Resource
Digital services often generate data through searches, transactions, interactions, usage patterns and operational activities.
When lawfully collected and responsibly managed, data can help businesses understand their customers, improve products and make better decisions.
For example, an online store might examine:
- Which products attract visits.
- Which product pages lead to purchases.
- Where customers abandon the checkout process.
- Which products generate returns.
- Which delivery problems recur.
- Which customer questions consume the most support time.
These observations can reveal opportunities to improve the business.
Data creates value through use
Data alone does not necessarily create economic value.
A business needs suitable data, a clear question, reliable analysis and the ability to act on the results.
The process looks like this:
DATA → ANALYSIS → INSIGHT → DECISION → ACTION → MEASURABLE RESULT
Suppose an online store discovers that customers frequently abandon checkout because delivery costs appear too late.
The business could display delivery costs earlier, improve the information provided before checkout and measure whether completion rates change.
The economic value comes from improving the customer experience and business outcome, not merely collecting more information.
Data also creates responsibilities
Businesses must consider privacy, security, accuracy, lawful processing, access controls, retention and applicable legal obligations.
Collecting unnecessary information increases risk without necessarily improving the product.
More data is not always better data.
Who captures the value created by data?
This is an important economic question.
A user may generate data through interactions with a platform. The platform may use aggregated or otherwise lawfully processed information to improve its services, sell advertising or support other business activities.
The user, platform, advertisers and other participants may receive different benefits.
The distribution of those benefits depends on the business model, contractual arrangements, market power, technology and applicable law.
This is one reason data governance and competition policy are important subjects in the digital economy.
For further reading, see UNCTAD's research on digital platforms and value creation in developing countries.
9. Understand Value Leakage: Where Business Opportunities Are Lost
Value leakage occurs when a business loses benefits, revenue, resources or economic opportunities through avoidable weaknesses in its operations or business model.
In digital businesses, leakage can happen at several stages.
Customer acquisition leakage
The business spends money attracting people who are unlikely to buy.
Possible responses include improving audience targeting, clarifying the offer and testing channels before increasing expenditure.
Conversion leakage
People visit the website or contact the business but do not complete the intended action.
Possible causes include unclear pricing, slow pages, complicated forms, poor mobile usability, weak trust signals or missing information.
The appropriate response is to identify the actual obstacle rather than assume that every problem requires more advertising.
Delivery leakage
The business wins customers but spends too much time correcting errors, repeating work or handling preventable support requests.
Better processes, documentation, automation and quality checks may reduce these costs.
Payment leakage
Customers receive products or services, but invoices remain unpaid, payment records are inaccurate or reconciliation is incomplete.
Clear payment terms, reminders and reliable records can help manage these problems.
Retention leakage
Customers leave because the product no longer meets their needs, support is poor or the service is unreliable.
Understanding why customers leave is often more useful than repeatedly paying to acquire replacements.
Ownership leakage
A business creates value but lacks control over important assets or relationships.
For example, it may depend entirely on one marketplace, lack access to its own business records or fail to secure rights to work created by contractors.
The correct response depends on the legal arrangements, platform rules and operational context.
A value-leakage audit
Ask the following questions:
- Where do potential customers abandon the buying journey?
- Which tasks consume time without improving customer outcomes?
- Which costs increase faster than revenue?
- Which errors or refunds occur repeatedly?
- Which payments remain uncollected?
- Why do customers stop using the service?
- Which platforms or suppliers could interrupt operations?
- Which assets, records or customer relationships are inadequately protected?
These questions help turn the abstract idea of value capture into practical business improvement.
10. Understand Value Creation in Developing Economies
The digital economy can help businesses and individuals participate in markets beyond their immediate location.
A skilled professional may deliver services remotely. A creator may distribute educational materials online. A software developer may build products for customers in multiple countries. A small business may use digital payments, online ordering and digital marketing to improve its operations.
However, being connected to a global market does not guarantee that a person or country captures a substantial share of the resulting economic value.
Participation versus value capture
Consider a digital platform that connects customers around the world with service providers in a developing country.
The local provider may receive revenue for completing the work. The platform may also collect transaction fees and benefit from its software, data, brand and customer relationships.
Other businesses may supply hosting, payment processing, advertising or other services.
The economic value is distributed among multiple participants.
The local provider's position depends on the service offered, bargaining power, skills, costs, competition, contractual terms and access to alternative channels.
This does not mean that platforms are inherently harmful. They can provide valuable access to customers and reduce certain barriers to market participation.
The important question is whether participation leads to sustainable benefits and whether local businesses can develop stronger capabilities over time.
Building the ability to capture more value
Individuals and businesses can work toward greater economic independence by developing:
- Specialized skills and expertise.
- Products or services that solve identifiable problems.
- Direct relationships with customers where appropriate.
- Stronger brands and reputations.
- Reusable intellectual property and business processes.
- Reliable financial and operational records.
- Multiple suitable distribution channels.
- Knowledge of pricing, costs and customer needs.
- The ability to maintain and improve their own digital assets.
These are not guarantees of success. They are capabilities that can improve a business's ability to create, deliver and retain value.
For broader context, consult the World Bank's overview of the digital economy.
11. Understand Why Digital Economy Measurement Is Difficult
The digital economy is not a single industry with perfectly clear boundaries.
A software company may produce digital services directly. A manufacturer may use digital systems to improve physical production. A retailer may sell through a combination of physical shops and online channels. A company may develop software internally rather than sell it to customers.
Should all of these activities be counted as part of the digital economy? If so, how much of their output should be attributed to digital technology?
Different measurement frameworks answer these questions in different ways.
The US Bureau of Economic Analysis has developed methods for estimating digital-economy activity, including digital infrastructure, e-commerce and priced digital services.
The OECD's work on digital supply-and-use tables seeks to improve the measurement of digital production, products and transactions within the wider economy.
These frameworks matter because a single headline figure may not capture all the ways digitalization affects productivity, employment, business models and economic activity.
For background, read:
- BEA — Defining and Measuring the Digital Economy
- OECD — Measuring the Digital Economy: Why Is It Important?
- OECD — The Going Digital Measurement Roadmap 2026
These sources are useful for understanding measurement methods. They should not be treated as interchangeable estimates of a single universally agreed number.
12. Build Your Own Digital Value Map
You can apply the principles in this chapter to a business idea, a website, a YouTube channel, a digital service or an existing company.
Create a simple value map using the following structure.
| Question | What to identify |
|---|---|
| Customer | Who experiences the problem? |
| Problem | What difficulty or unmet need do they have? |
| Current alternative | How do they solve it today? |
| Proposed solution | What will you provide? |
| Customer benefit | What improves, and how will you know? |
| Delivery | How will customers receive and use the solution? |
| Distribution | How will the right customers discover it? |
| Revenue model | Who pays, how much, and how often? |
| Direct costs | What does each sale or delivery cost? |
| Operating costs | What must be paid even when sales are low? |
| Retention | Why would customers return or renew? |
| Control and risk | Which assets, systems or relationships could become points of dependence? |
Do not treat this as a formality. Use the answers to identify the assumptions that could make or break the idea.
Example: A digital service for local businesses
Suppose you want to offer website and automation services to small businesses.
Your value map might look like this:
Customer: local businesses that receive enquiries through several channels.
Problem: enquiries are missed, follow-ups are inconsistent and staff spend too much time repeating administrative tasks.
Solution: a mobile-friendly website, structured enquiry forms and an appropriate follow-up workflow.
Customer benefit: fewer missed enquiries, clearer information and less manual work.
Delivery: initial setup, training, maintenance and support.
Distribution: direct outreach, referrals, relevant educational content and partnerships.
Revenue model: an agreed implementation fee plus a recurring maintenance arrangement if ongoing work is required.
Costs: development time, hosting, software, support, customer acquisition and administration.
Retention: reliable performance, useful improvements, clear communication and measurable customer benefit.
Control and risk: documented ownership, secure access, reliable backups and an exit plan if a third-party service changes its terms.
This map exposes the business logic before substantial time and money are committed.
It also makes the proposal easier to explain to customers because it connects the service to a real operational need.
13. Test the Business Model Before Scaling
A common mistake is investing heavily in a product before confirming that customers want it and that the business can deliver it sustainably.
A more disciplined approach is to test the most important assumptions in stages.
Step 1: Verify the problem
Speak with potential customers. Ask how they currently handle the problem, how often it occurs, what it costs them and what they have already tried.
Avoid leading questions that encourage people to praise your idea.
Step 2: Test the proposed solution
Show a prototype, sample workflow, demonstration or clearly defined service proposal.
Determine whether the solution actually addresses the problem.
Step 3: Test willingness to pay
Where appropriate, offer a real, clearly described paid pilot or service engagement.
Compliments, social-media likes and survey interest are not equivalent to a completed purchase.
A small number of paying customers can provide useful evidence, although they do not automatically prove that the business can scale.
Step 4: Measure delivery costs
Record the time, software, infrastructure, support and other resources required to serve each customer.
Include your own labour rather than assuming that your time has no economic cost.
Step 5: Examine customer outcomes
Determine whether customers receive the promised benefit.
Use credible measures, such as time saved, error reduction, completed transactions, improved response times or customer retention, where appropriate.
Step 6: Improve the model
If the product is useful but unprofitable, examine pricing, delivery methods, costs and customer fit.
If the economics work but customers cannot discover the product, improve distribution.
If customers buy once but do not return, investigate whether the product delivers continuing value or whether a one-time purchase model is more appropriate.
Step 7: Scale only when the evidence supports it
Scaling increases the volume of activity. It can also magnify weak processes, poor margins and customer-support problems.
First establish that the product solves a real problem and that the business can deliver it reliably at a sustainable cost.
14. Your Practical Assignment: Analyse One Digital Business
Choose one business you understand. It could be a blog, online store, software service, YouTube channel, digital agency, educational platform or local business using digital technology.
Answer these questions:
- What customer problem does the business solve?
- Who receives the primary benefit?
- How does the business deliver that benefit?
- How do customers discover the business?
- What does the business charge for, if anything?
- Which other participants contribute to delivering the service?
- What are the main costs?
- What could prevent the business from capturing enough value to survive?
- What makes customers return or recommend it?
- Which customer benefit could be measured more clearly?
- Which platform, supplier or distribution channel creates a significant dependency?
- What is one improvement that could increase customer value or reduce avoidable costs?
Then draw this simple flow:
CUSTOMER PROBLEM → SOLUTION → DISTRIBUTION → CUSTOMER OUTCOME → REVENUE → COSTS → SUSTAINABLE VALUE
If you cannot explain the connection between these stages, you may understand the technology without yet understanding the business model.
That is a useful discovery. It tells you what to investigate next.
Conclusion: Build Systems That Create Value and Capture It Responsibly
The digital economy contains far more than online transactions, popular applications and technology companies.
It is an interconnected economic system in which digital infrastructure, software, data, platforms, skills and markets help people and organizations produce, deliver and exchange value.
For entrepreneurs, developers, creators and business owners, understanding this system means looking beyond the act of building something.
A sustainable digital business must identify a meaningful customer problem, develop an effective solution, deliver it reliably, reach the right audience, select an appropriate revenue model and manage the costs and risks involved.
It must also understand where control resides: who owns the product, who controls access to customers, which systems the business depends on and how the resulting economic value is distributed.
The core principle is:
CREATE VALUE THAT MATTERS. DELIVER IT RELIABLY. CAPTURE ENOUGH VALUE TO SUSTAIN THE WORK.
Use that principle to evaluate digital business ideas before investing heavily, to improve existing operations and to identify opportunities where technology can solve real economic problems.
The objective is not merely to participate in the digital economy.
It is to understand how it works well enough to build useful products, stronger businesses and durable economic value.
W3 NOTES BLOG | The Internet Money Feed
READ. USE. SOLVE.
Image: Springer Nature
.png)
No comments:
Post a Comment