Knowing how to search scientific literature is a core skill for anyone doing research. A structured search helps you find relevant, high-quality studies quickly instead of drowning in irrelevant results. This guide walks through the tools and techniques that make literature searching systematic and repeatable, from choosing a database to combining terms with Boolean operators.
This is an educational guide to research tools; verify details against each tool official documentation.
What is a literature search
A literature search is a systematic process of locating published studies, reviews, and other scholarly work on a specific topic. Instead of typing a full question into one box and hoping for the best, you break your topic into concepts, translate those concepts into search terms, and query a database in a controlled way.
Two of the most widely used starting points are PubMed and Google Scholar. PubMed is a free database of biomedical and life-sciences literature from the US National Library of Medicine (PubMed). Google Scholar is a freely accessible search engine that indexes scholarly literature across many disciplines (Google Scholar). PubMed is a strong first choice for clinical and biomedical questions, while Google Scholar is useful for broad, cross-disciplinary scoping.
How to search scientific literature step by step
Follow this sequence to move from a vague topic to a focused, reproducible search.
Step 1: Define your question and key concepts
Write your research question in plain language, then underline the two to four core concepts. For a clinical question these often map to a population, an intervention, and an outcome. These concepts become the building blocks of your search.
Step 2: List search terms and synonyms
For each concept, list the words and phrases authors might use, including synonyms, abbreviations, and spelling variants. A single concept may need several terms so you do not miss studies that use different wording.
Step 3: Combine terms with Boolean operators
Join your terms using Boolean logic. The operators AND, OR, and NOT combine or exclude search terms to refine results (PubMed Help). Use OR to gather synonyms for the same concept, AND to require that different concepts appear together, and NOT to remove an unwanted topic.
Step 4: Add controlled vocabulary
Where a database supports it, add controlled vocabulary terms alongside your keywords. In PubMed, MeSH (Medical Subject Headings) is the NLM controlled vocabulary used to index PubMed articles (MeSH). Searching with MeSH terms helps you capture articles on a concept even when authors used different words in the title or abstract.
Step 5: Choose the right database
Match the database to your question. Start in PubMed for biomedical and clinical topics (PubMed), and use Google Scholar to scope broadly across many fields or to find work outside the biomedical literature (Google Scholar). Running the same core search in more than one place reduces the chance of missing relevant studies.
Step 6: Apply filters and refine
Narrow your results with the filters the database offers, such as publication type, date range, or language. Review the first pages of results, note useful new terms you had not considered, and fold them back into your search to improve it.
Step 7: Screen, save, and track
Screen titles and abstracts against clear inclusion criteria, save the studies you keep, and record your final search terms and filters. Documenting the exact query makes your search transparent and repeatable for others or for a later update.
Key search tools compared
| Tool | What it is | Best used for |
|---|---|---|
| PubMed | A free database of biomedical and life-sciences literature from the US National Library of Medicine (PubMed) | Clinical and biomedical questions |
| Google Scholar | A freely accessible search engine that indexes scholarly literature across many disciplines (Google Scholar) | Broad, cross-disciplinary scoping |
| MeSH | The NLM controlled vocabulary used to index PubMed articles (MeSH) | Precise, concept-based PubMed searches |
| Boolean operators | AND, OR, and NOT that combine or exclude search terms (PubMed Help) | Refining and controlling result size |
Common mistakes to avoid
- Searching with only one keyword per concept and missing studies that use synonyms.
- Relying on keywords alone and skipping controlled vocabulary such as MeSH in PubMed.
- Mixing concepts with the wrong Boolean operator, for example using AND where OR was needed to gather synonyms.
- Searching a single database and assuming it covers everything relevant.
- Failing to record the final search terms and filters, which makes the search impossible to reproduce.
How Phở helps
Phở includes a live Find Papers feature that runs your search across PubMed, ClinicalTrials.gov, EuropePMC, and Semantic Scholar from one place. Results come back grounded in the real retrieved sources with clickable citations, and Phở follows a cite-or-abstain rule, labeling a claim as unverified rather than guessing when it cannot find support. This keeps your literature search fast to run and transparent to check. Once you have gathered your studies, the next steps are usually to appraise the quality of the evidence and, for primary data, to analyze your research data.
References
- (PubMed), US National Library of Medicine
- (Google Scholar)
- (PubMed Help)
- (MeSH), US National Library of Medicine