How to Cite Sources
The question of citation is perhaps the biggest nightmare for most students writing their thesis. When should you cite? How should you format it? What's the difference between APA and Harvard style? And what if you accidentally miss something – is that already plagiarism? If these questions are running through your mind, you're in the right place.
In this article, I'll explain in detail how academic citation works, what citation styles exist, and show you through practical examples how to apply them. By the end of this article, you'll confidently know when and how to cite – and you'll never have to worry about plagiarism again.
📚 What you'll learn from this article:
- • Why citation is essential in your thesis
- • When you MUST and when you DON'T need to cite
- • The most common citation styles (APA, Harvard, IEEE, Chicago)
- • Handling direct quotations vs. paraphrasing
- • Creating a reference list for different source types
- • Using reference management software
- • The most common citation errors and how to avoid them
Why is citation so important?
Before diving into the technical details, let's talk about why citation is so important. Many people think it's just a bureaucratic requirement, but it's actually a fundamental pillar of academic work.
1. Avoiding plagiarism
The most obvious reason: if you use others' thoughts and words without citation, that's plagiarism. Plagiarism is not only ethically unacceptable but can have serious consequences: thesis rejection, disciplinary action, or even revocation of your degree. Plagiarism detection software (Turnitin, Urkund) is increasingly sophisticated and catches almost everything.
2. Credibility and foundation
When you cite, you show that your claims aren't pulled out of thin air but are based on academic sources. This is especially important in the theoretical background and literature review sections. Proper citations indicate that you're familiar with the scholarly literature in your field.
3. Academic integrity
Citation is also a way of paying respect to those who worked on the topic before you. Academic work always builds on previous results – citations make this continuity visible.
4. Informing the reader
Citations allow anyone who reads your thesis to find the original sources. This is particularly useful if someone wants to dig deeper into the topic.
⚠️ Important to know!
Lack of citation can be a problem even when it's not intentional fraud. If you simply forget to cite or don't know how to do it, that can still qualify as plagiarism. That's why it's important to consciously manage every source from the very beginning of your writing!
When should you cite?
This is one of the most common questions. Many people either cite too much or too little. Let's look at exactly when you need to cite and when you don't.
You MUST cite when:
- You quote directly – If you use someone's exact words, you must put them in quotation marks and cite the source (with page number).
- You paraphrase – If you describe others' ideas in your own words, that also requires citation. Paraphrasing doesn't exempt you from citing!
- You mention data or statistics – Every specific piece of data, number, or statistic must have its source cited.
- You reference theories or models – If you mention a recognized theory (e.g., Maslow's hierarchy of needs), cite the original source.
- You include images, figures, or tables – Even if you modify them, the source must be cited.
- You make controversial claims – If you claim something that isn't generally accepted, support it with sources.
You DON'T need to cite when:
- You mention common knowledge – "Water boils at 100°C" or "Hungary became a democratic state in 1989" – these are general facts.
- You describe your own research results – The results of your own questionnaire, interviews, and observations are your work.
- You express your own opinion and conclusions – The evaluative and analytical parts of your thesis are your own thoughts (but they should still be supported by previously cited evidence).
💡 Practical rule:
When in doubt, cite! It's better to "over-cite" than to miss an important source. An examiner will never deduct points for being too thorough with citations.
The most common citation styles
There are numerous citation styles, each with its own logic and area of use. The most important thing is to use ONE style consistently throughout your entire thesis. Let's look at the most common ones!
APA 7 (American Psychological Association)
APA is the most widespread style in social sciences and psychology, but many universities also prefer it in other disciplines. The 7th edition is the latest version.
In-text citation:
One author: (Smith, 2023)
Two authors: (Smith & Jones, 2023)
Three or more authors: (Smith et al., 2023)
Direct quote: (Smith, 2023, p. 45)
Multiple sources: (Smith, 2023; Jones, 2022)
Reference list format:
Book:
Smith, J. (2023). Research methods in social sciences. Academic Press.
Journal article:
Jones, A., & Brown, B. (2022). The role of motivation in education. Educational Review, 72(3), 45–62. https://doi.org/10.1234/example
Website:
National Center for Education Statistics. (2026, March 15). Education statistics digest 2023. https://www.nces.ed.gov/example
Book chapter:
Williams, L. (2021). Qualitative methods. In E. Taylor (Ed.), Research methodology (pp. 123–145). Sage Publications.
Harvard style
The Harvard style is very similar to APA but has some minor differences. It's mainly popular in the United Kingdom and business sciences.
Main differences from APA:
- No comma between author and year: (Smith 2023)
- Colon before page number: (Smith 2023: 45)
- "and" or "&" between two authors (depends on university)
IEEE style
The IEEE (Institute of Electrical and Electronics Engineers) style is mainly used in engineering and computer science fields. It's a numbered system.
In-text citation:
Citations appear as numbers in square brackets: [1], [2], [1]–[3]
Reference list format:
[1] J. Smith, "Applications of artificial intelligence," Computer Science Review, vol. 15, no. 3, pp. 45–62, 2023.
Chicago style
The Chicago style exists in two versions: author-date (in-text) and notes-bibliography (footnotes). The footnote version is common in humanities and history.
Notes-bibliography version:
Numbers in superscript in the text: "The research findings show1..."
1 John Smith, Academic Research Methods (New York: Academic Press, 2023), 45.
| Style | Format | Typical field |
|---|---|---|
| APA 7 | (Author, Year) | Social sciences, psychology |
| Harvard | (Author Year) | Business, UK generally |
| IEEE | [Number] | Engineering, computer science |
| Chicago | Footnote or (Author Year) | Humanities, history |
| MLA | (Author Page) | Literature, linguistics |
Direct quotation vs. paraphrasing
You can use both in your thesis, but it's important to know when to use which.
Direct quotation
Use it when:
- The wording is particularly important or apt
- You're quoting a definition
- The precise meaning of the author's words matters
- You're arguing against or analyzing the quoted text
Short quotation (fewer than 40 words – APA):
Smith (2023) argues that "motivation plays an indispensable role in the learning process" (p. 45).
Long quotation (40 words or more – APA):
In a separate paragraph, indented, without quotation marks:
Paraphrasing
Paraphrasing means expressing others' ideas in YOUR OWN WORDS. This is generally preferred over direct quotation because it shows that you've understood and processed the source.
✅ Correct paraphrasing:
Original: "Motivation plays an indispensable role in the learning process."
Paraphrase: Smith (2023) emphasizes that students' internal drive fundamentally influences their academic success.
❌ Incorrect paraphrasing (plagiarism!):
Original: "Motivation plays an indispensable role in the learning process."
Bad: Motivation plays an essential role in the learning process (Smith, 2023).
This is just synonym substitution, not true paraphrasing!
Citing different source types
Not all sources are the same. Let's see how to cite different types of sources in APA 7 style (the most common).
📕 Printed book
Author, A. A. (Year). Book title. Publisher.
Example: Smith, J. (2023). Research methodology. Academic Press.
📖 E-book (with DOI)
Author, A. A. (Year). Book title. Publisher. https://doi.org/xxxxx
📰 Journal article (online, with DOI)
Author, A. A., & Author, B. B. (Year). Article title. Journal Name, volume(issue), pages. https://doi.org/xxxxx
Example: Jones, A., & Brown, B. (2022). The effects of stress. Psychological Review, 15(3), 45–62. https://doi.org/10.1234/example
🌐 Website (with known author)
Author, A. A. (Year, Month Day). Page title. Website Name. URL
Example: Williams, J. (2026, January 15). Digital education trends. Education Online. https://example.com/article
🏛️ Website (organization as author)
Organization Name. (Year, Month Day). Page title. URL
Example: National Center for Education Statistics. (2026, March 1). Population data. https://nces.ed.gov/example
📹 YouTube video
Channel Name. (Year, Month Day). Video title [Video]. YouTube. URL
📜 Legislation
Name of Act, Public Law Number, Volume Source § Section Number (Year).
Example: Higher Education Act of 1965, 20 U.S.C. § 1001 et seq. (1965).
🎓 Thesis, dissertation
Author, A. A. (Year). Thesis title [Type, Institution]. Database Name.
Reference management software
If you try to manage all your citations manually, sooner or later you'll get confused. Reference management software makes your life easier: it saves your sources, automatically generates in-text citations and reference lists, and switches styles with one click.
| Software | Price | Advantages | Disadvantages |
|---|---|---|---|
| Zotero | Free | Open source, browser plugin, Word integration | 300 MB free storage |
| Mendeley | Free (basic version) | PDF reader, social features | Owned by Elsevier, 2 GB limit |
| EndNote | Paid | Professional, detailed features | Expensive, complex |
| Citavi | Free (for students) | Excellent knowledge management | Windows only |
💚 My personal recommendation: Zotero
It's free, open source, and can do everything you need. With the Zotero Connector browser extension, you can save websites, books, and articles with a single click. The Word plugin automatically inserts citations and generates your reference list.
- Download Zotero: zotero.org
- Install the Zotero Connector browser extension
- In Word: Zotero tab → Add/Edit Citation
- At the end of your thesis: Add/Edit Bibliography
The most common citation errors
Based on years of experience, these are the most common mistakes students make:
❌ 1. Inconsistent style
Sometimes APA, sometimes Harvard, sometimes a unique format. This is a serious error!
✅ Solution: Choose ONE style and use it throughout. Use a reference manager!
❌ 2. Missing page number in quotations
Page numbers are mandatory for direct quotations!
✅ Solution: Include page numbers for every quotation: (Smith, 2023, p. 45)
❌ 3. Broken URLs
Links to online sources often become outdated or change.
✅ Solution: Check all links before submission! Use archived versions (web.archive.org).
❌ 4. Wikipedia as a source
Wikipedia is not a primary academic source.
✅ Solution: Use Wikipedia's references as a starting point, but cite the original sources!
❌ 5. Too many quotes, too little original thought
If your thesis consists only of quotes, it doesn't show your own thinking.
✅ Solution: Work with paraphrasing and connect sources with your own analysis!
❌ 6. Reference list and text don't match
There's a citation in the text but not in the reference list, or vice versa.
✅ Solution: Use reference management software, or manually check before submission!
Practical checklist
✅ Citation checklist before submission:
In-text citations
- ☐ Every quote and paraphrase is cited
- ☐ Quotes include page numbers
- ☐ Style is consistent throughout
- ☐ No missing year or author
Reference list
- ☐ In alphabetical order
- ☐ Format is consistent throughout
- ☐ All in-text citations are included
- ☐ No unused sources included
Online sources
- ☐ All URLs work
- ☐ Access date is included (if required)
- ☐ Using DOI instead of URL where available
General
- ☐ Following my university's requirements
- ☐ Checked with plagiarism software
- ☐ At least 15-20 sources included
Summary
Citation isn't complicated – it just requires attention and consistency. If you follow the basic rules (always cite when using others' ideas; choose one style and stick to it throughout; use reference management software), you have nothing to worry about.
The most important message: citation isn't your enemy, it's your friend. It helps you avoid plagiarism, adds credibility to your work, and shows that you're familiar with the scholarly literature in your field. The earlier you get used to conscious source management, the easier your life will be not only with your thesis but with all future academic work as well.
🎯 Tl;dr – what you must remember:
- 1. Always cite when using others' ideas – whether directly quoted or paraphrased
- 2. Choose ONE citation style (as required by your university) and use it throughout
- 3. ALWAYS include page numbers for direct quotations
- 4. Use reference management software (Zotero is free and excellent)
- 5. Before submission, verify that all citations are in the reference list
- 6. When in doubt, cite! It's better to "over-cite" than to miss something
Good luck with your citations! If you're still uncertain, check your university library's online guides – most institutions provide detailed instructions for their specific requirements. 📖