Writing a focused literature review is a crucial part of any academic or research-based project. One of the most common questions students and early-career researchers ask is: “How many sources should a focused literature review have?” While the exact number depends on various factors, this article explores practical guidelines, academic expectations, and expert insights to help you make an informed decision.
Why the Number of Sources Matters in a Literature Review
A well-constructed literature review offers more than just a summary of existing research. It helps:
- Build a theoretical foundation for your study
- Identify gaps in the literature
- Provide context for your research problem
- Justify the need for your study
Having too few sources can weaken your argument, while too many irrelevant sources may dilute your focus. Therefore, determining the right number of sources is essential for writing an effective and targeted literature review.
For general strategies on organizing literature, visit the UNC Writing Center’s Guide on Literature Reviews
How Many Sources Should a Focused Literature Review Include?
There is no fixed number, but academic conventions and field-specific expectations offer some benchmarks.
General Guidelines Based on Academic Level
The number of sources required for a literature review can vary depending on the academic level of the research. For an undergraduate paper, it’s common to use around 8–20 scholarly sources, as the focus is often on summarizing existing research. In a master’s thesis, the number of sources increases to 20–50+ sources, reflecting the need for a more in-depth analysis and broader understanding of the topic. For a doctoral dissertation, a thorough review usually demands 50–200+ sources, as the research requires comprehensive coverage and the establishment of a robust theoretical framework.
These are approximate figures, not rigid rules. The depth, scope, and topic complexity ultimately determine how many sources your review should include.
Factors That Influence the Number of Sources
1. Scope of the Research Topic
Narrow or highly specialized topics generally require fewer sources, while interdisciplinary or broad topics need a more extensive base.
2. Stage of Academic Research
An early-stage term paper might need fewer references than a thesis or journal article.
3. Field of Study
STEM disciplines might rely on fewer but more recent studies, while social sciences and humanities may require a deeper historical perspective and more citations.
4. Type of Literature Review
- Systematic Reviews may include 50–100+ sources due to exhaustive coverage.
- Narrative Reviews or focused literature reviews might include 15–30 high-quality sources.
Explore more about different review types in our article on Systematic vs. Narrative Literature Reviews.
Quality Over Quantity: What Makes a Source Valuable?
It’s not just how many sources you cite—it’s how relevant and credible they are.
What to Look For:
- Peer-reviewed journals
- Recent publications (preferably within the last 5–10 years)
- Seminal works in the field
- Reputable publishers (SAGE, Elsevier, Springer, etc.)
Avoid overloading your literature review with outdated or marginally relevant materials. Instead, focus on building a strong narrative around key arguments and evidence.
Check Google Scholar or PubMed for access to credible academic sources.
How to Strategically Organize Your Literature
To make your literature review readable and academically sound:
Use Categorization Techniques:
- Chronological: Track how research has evolved over time
- Thematic: Group studies by themes or subtopics
- Methodological: Classify based on research methods used
- Theoretical: Organize by conceptual frameworks
Learn more in our guide on How to Organize Sources for an Effective Literature Review.
Tools to Help Manage and Track Sources
If you’re handling 20–100+ references, use AI-powered tools to manage and cite them efficiently:
Recommended Tools:
- Zotero or Mendeley for citation management
- ResearchPal Reference Generator – Our AI-powered citation tool helps you create citations in seconds
- Grammarly – Assists with paraphrasing and citation clarity (Grammarly’s Plagiarism Checker)
Common Mistakes to Avoid
- Citing irrelevant sources just to boost numbers
- Using only outdated studies
- Ignoring grey literature when appropriate (e.g., government or NGO reports)
- Failing to update your sources during multiple review stages
Also explore our article on How to Critically Analyze Research Studies to strengthen your evaluation process.
Final Thoughts: So, How Many Sources Should You Use?
A focused literature review typically requires 15–40 strong, well-vetted sources, depending on your project’s scope and depth. The key is to strike a balance: include enough references to support your research, but not so many that your paper becomes unfocused.
Remember: quality, relevance, and synthesis are more valuable than volume. Using the right tools, strategies, and research techniques will make your literature review insightful and impactful.
