Most health-sciences reviews use 25–60 sources; capstone theses often span 60–150 with scope and methods driving the count.
A reader wants a clear answer fast. If you’re sizing the reading load for a review in medicine, nursing, public health, pharmacy, or allied fields, the short rule is this: match the number of references to the question, the method, and the venue. Tight, topic-bound assignments land in the few-dozen range. Graduate dissertations and journal-ready reviews draw on dozens to well over a hundred. The goal is coverage, not a quota.
Recommended Source Counts For Health Sciences Reviews
There’s no universal minimum across journals or universities. Editors and supervisors judge the depth of your search and the fitness of each paper. Still, patterns repeat across departments. The table below shows practical ranges that align with common expectations in health research writing. Use it to map your target before you search.
| Project Type | Typical Range | Scope Notes |
|---|---|---|
| Short Course Paper (1,500–3,000 words) | 15–30 | One clinical question; narrow time window or population. |
| Upper-Level Undergrad Review | 25–45 | Multiple subtopics; mix of trials, cohort studies, and summaries. |
| Master’s Thesis Background | 40–80 | Broad map of the field plus a deep lane tied to the research aim. |
| DNP/MPH Capstone | 60–120 | Practice guidelines, trials, quality-improvement reports, grey literature. |
| Journal Narrative Review | 50–100+ | Wide read across designs; expert synthesis and clinical context. |
| Systematic Review (no meta-analysis) | 80–200+ | Large search set; strict screening; final set depends on criteria. |
| Systematic Review With Meta-analysis | 100–300+ total refs; 5–30 included studies | Search yields many records; included study count follows eligibility. |
Why these bands? Health topics sit on decades of trials, registries, and observational work. A brief paper can’t process all of that, so it samples the most representative studies for each claim. A thesis or journal review often traces the full chain from early trials to recent updates, which naturally bumps the count.
What Editors And Assessors Look For
Markers of quality matter more than raw totals. Readers want transparent search steps, appropriate databases, clear inclusion rules, and a sound read of study quality. These cues align with common guidance in the review world, such as PRISMA 2020 for reporting and the Cochrane approach to searching and selection. When you show how you searched and why you kept each paper, your reference list earns trust.
Depth Over Volume
Pick the most relevant and up-to-date studies for each key point. The APA guidance on citation levels notes that literature reviews often include a broader set of references, yet it still favors citing the best exemplars for each claim. That balance keeps the list strong without padding.
Included Studies Versus Total References
For systematic work, your final list usually includes two groups: the studies that meet criteria and the contextual items (methods papers, prior reviews, guidelines, trial registries). A meta-analysis may include only a handful of trials but still cite hundreds of items across methods and background. Reporting standards ask you to show the flow from initial records to included studies.
How To Set Your Target Range
Start with your review type, then tune for topic breadth and audience. The steps below give a concrete plan that keeps the list tight and credible.
1) Define The Review Type
Narrative review: A broad synthesis that surveys themes, debates, and practice takeaways. Expect dozens to about a hundred references, more if the topic spans subfields or long time spans.
Scoping review: Maps volume and nature of evidence across populations, interventions, and outcomes. Source counts grow with breadth; the included-study set can still be modest.
Systematic review: Pre-planned question, protocol, comprehensive search, dual screening, and risk-of-bias appraisal. The reference list balloons due to search reporting and appendices.
2) Gauge The Topic Breadth
A narrow clinical question (one setting, single outcome) needs fewer items than a cross-cutting public health theme. Add more sources when you have multiple populations, interventions, comparators, or outcomes. Trim when the topic is tightly bounded by a specific guideline or drug class.
3) Match The Venue
Course paper? Hit the range for that credit level. Thesis or dissertation? Plan for double or triple the course paper range, since committees expect fuller canvassing across decades and methods. Journal review? Read recent articles in the target journal and mirror their depth.
4) Plan The Search
In health research, database choice drives both the count and the quality of hits. A strong core set usually includes MEDLINE/PubMed and Embase, plus CINAHL for nursing and allied health, PsycINFO for mental health, and CENTRAL for trials. Public health topics often add Web of Science for citation chasing and regional indexes for coverage.
5) Track The Flow
Keep a log of records identified, screened, and included. Use a flow diagram to show the path from search to final set. PRISMA-style diagrams are standard for systematic work and are helpful even for structured narrative reviews.
What Counts As “Enough” For Health Topics
Enough means the reader can see the state of evidence, weigh the strengths and gaps, and act. The list should include landmark trials, key observational cohorts, key guidelines, and the best recent updates. It should not drown the reader in duplicates or marginal items. The checks below help you know when to stop.
Coverage Checks
- Each claim in the text traces to one or two high-quality sources.
- Each major design in the field appears at least once (trial, cohort, case-control, qualitative, as relevant).
- Key guidelines and data registries are present for practice-facing topics.
- Recent years are represented; older classics appear only when they still shape care or methods.
Red Flags That Signal Too Few
- Large claims rest on a single small study.
- Only one database was searched for a topic with cross-index coverage.
- No landmark trials or no major cohort studies appear in the list.
- The same authors and lab groups recur without balance.
Red Flags That Signal Too Many
- Multiple citations say the same thing with no new angle.
- Old studies crowd out recent syntheses.
- Reference padding to hit a number, not to inform the reader.
Setting Ranges With Transparency
Editors in health journals care about method more than length. PRISMA 2020 asks for clear reporting of the search and selection steps for systematic work, and Cochrane’s handbook chapters lay out similar expectations for searching and reporting. If your process is clear, your range is easier to defend.
Database And Source Planning
Pick sources that map to your question. A clinical drug question rides on randomized trials and safety reports; a service-delivery question leans on mixed-methods work across care settings. Public health topics often need policy reports and surveillance data. The checklist below helps you shape the mix.
| Source Type | When It Helps | Examples |
|---|---|---|
| Biomedical Databases | Intervention, diagnosis, prognosis, harms. | MEDLINE/PubMed, Embase, CENTRAL. |
| Nursing/Allied Health | Care models, staffing, practice change. | CINAHL. |
| Mental Health | Psychometrics, therapy trials, comorbidity. | PsycINFO. |
| Public Health | Policy, programs, surveillance. | Web of Science, Scopus; government reports. |
| Grey Literature | Guidelines, theses, reports, trial registries. | NICE guidance, WHO docs, clinicaltrials.gov. |
| Citation Chasing | Fill gaps and find missed items. | Backward/forward searches. |
How To Right-Size Your List In Practice
Use a staged approach that starts wide and narrows to the best set for your purpose.
Stage 1: Map The Field
Run scoping searches in two to four core databases. Skim titles and abstracts to gauge volume and recurring terms. Note the main outcomes and the time span of active research.
Stage 2: Set A Working Target
Pick a provisional reference range based on the ranges in the first table. Share it with a supervisor or co-author. Align on what “coverage” means for this topic and venue.
Stage 3: Screen With Inclusion Rules
Write crisp rules for population, intervention/exposure, comparator, outcome, study design, and timeframe. Apply them to abstracts, then to full texts. Keep a log of reasons for exclusion.
Stage 4: Balance The Mix
Check for recency, design variety, and setting diversity. Trim duplicates and studies that add no new angle. Add missing designs or groups as needed.
Stage 5: Finalize And Document
Write the search paragraph, list the databases, add date limits, and include the flow of records. Attach the strategy or put it in an appendix if the venue asks for it.
Common Scenarios And Practical Answers
“My Assignment Caps The Paper At 2,500 Words.”
Plan for 15–30 references. Pick the best evidence for each claim and one or two syntheses for broad context. Keep methods short and clear.
“My Thesis Committee Wants A Complete Background.”
Plan for 60–120 references across study designs and key guidelines, with heavy use of recent syntheses. Expect to add older landmark trials if they still shape care.
“We’re Submitting A Systematic Review.”
There’s no fixed number of included studies. Some questions produce five to ten eligible trials; others yield dozens. What matters is a comprehensive search and clear eligibility. Your total reference list will include search methods papers, prior reviews, and supporting documents in addition to the included studies.
Quality Signals That Raise Confidence
Quick Audit Checklist
- Databases match the question domain.
- Eligibility rules are stated and applied.
- Risk-of-bias or quality appraisal is present when needed.
- Recent years are covered, with clear dates for last search.
- Citations back every key claim and table entry.
When A Small Number Works
Some topics have very few trials or only early observational work. A tight review can still pass if it states the limits and points to live studies or registries. In such cases, depth of reading and clarity of limits matter more than a big list.
Bottom Line For Planning
Pick a target that fits the task, then prove your process. Most health-sciences reviews fall in the 25–60 range; bigger projects and journal reviews run 60–150 or more. Tie every extra citation to a clear gain in coverage or clarity. That way your reader sees value, not volume.