Finding sources for a literature review: step-by-step
Start with a tight question. Pin down the scope, the population, the setting, the time window, and any outcomes or measures that matter to your field. Write the question in one line, then draft two shorter versions: one broad, one narrow. Those three versions guide every search choice you make.
Next, list the core concepts. Under each concept, add synonyms, spelling variants, and acronyms. Split general words from terms that belong to one discipline. This map turns into search strings in the next section, and it keeps you from chasing the same word in circles.
Pick the right places to search
Different tools surface different records and formats. Mix a multi-disciplinary index with at least one subject database, and layer in grey literature where needed. Use your library portal to reach paid databases that sit behind a login.
| Source | What it covers | When it helps |
|---|---|---|
| Google Scholar | Scholarly articles, theses, books, preprints, and more | Fast scoping, “Cited by” chains, quick full-text links |
| Subject databases | Curated records with subject tags (e.g., PubMed, PsycINFO, ERIC) | Precise topic searches using controlled vocabulary and filters |
| Scopus or Web of Science | Citation indexes across many fields | Forward and backward citation chasing, author and journal tracking |
| Library catalog | Books, ebooks, and reference works | Background reading, theory, and methods chapters |
| Theses and dissertations | Graduate work and deep bibliographies | Emerging topics, methods details, granular keywords |
| Grey literature | Reports, guidelines, policy briefs, conference papers | Practice insights, local data, and items outside journals |
Add one more route: expert picks. Skim recent handbooks, field guides, and top journals. Note recurring authors, labs, and research groups. Keep a shortlist of names to follow across databases.
Build search strings that actually work
Your word map becomes a set of clean strings. Use phrase marks, Boolean logic, truncation, and field limits. Test a broad string first, then refine the parts that flood you with noise.
Use Boolean logic and phrase marks
AND narrows by combining concepts. OR groups synonyms. NOT removes a branch you do not want. Quotes lock a phrase. An asterisk grabs word endings. Many systems accept parentheses to control the order.
Say you need sources on school-based mindfulness for teens. A first pass could be: “mindfulness” AND (adolescen* OR teen* OR youth) AND (school* OR classroom). If results include clinical settings you do not need, add NOT (clinic* OR hospital*). If you see lots of yoga content, add NOT yoga. Keep changes small and test one tweak at a time.
Work with controlled vocabulary
Subject databases tag records with official headings. In biomedicine those are MeSH terms. In education and psychology, databases carry their own thesauri. Add these headings to your strings, then pair them with free-text keywords to catch fresh records that are not tagged yet.
Filters that save time
Use date ranges to match your assignment or protocol. Use study type filters only when they are reliable in your database. Be careful with “full text” filters in broad tools, since those can hide paywalled items that your library still provides through links.
Ways to find sources for a literature review online
Start wide on a multi-disciplinary tool to spot language and landmark papers, then move into a subject database for precision. Save promising records to a folder or a reference manager. Export the full citation and the abstract so you can screen later without re-searching.
Follow the citation trail
Open two paths for every strong paper. First, scan its reference list to move backward in time. Second, use “Cited by” to move forward and see who built on it. This two-way path expands one good hit into a cluster of related work fast.
Balance speed with quality
Quick scans on broad tools help you learn the language of the topic. The fine work happens in subject databases, where you can target methods, populations, and measures with tags and fields. Blend both styles so you move fast without losing precision.
Know when to stop
Stop when new searches repeat the same names and titles, your strings retrieve only minor variations, and your notes show coverage across key years, venues, and viewpoints. That plateau signals you have reached practical saturation for this review.
Turn hits into a clean reading list
Create a simple screening rule. Keep items that match your topic, population, setting, and time window. Exclude items that miss two or more of those. Note the rule at the top of your notes so your choices stay consistent.
Skim fast, then decide
Read the title and abstract, then the methods section. Look for clear aims, fit to your question, and data you can use. Tag each item yes, no, or maybe. Add two tags that matter to you, such as method or region. Short tags keep the pile tidy when it grows.
Record what you did
Tracking your steps helps you rerun a search or explain choices in a methods section. Log the database, the exact string, the date, and the number of hits. Keep notes tidy. Save screenshots of key filters if the interface makes strings hard to read.
Keep your search strings tidy
Store tested strings in a plain text file and in your reference manager. Label each with the tool name and date. Keep a “broad” and a “precise” version for each concept set so you can pivot based on the task at hand.
Patterns you can reuse
General pattern: (Concept A terms) AND (Concept B terms) AND (Concept C terms). Synonyms live inside parentheses joined by OR, with quotes for phrases. Trim NOT terms only after you have sketched the noise you want to avoid.
Field-targeted pattern: title/abstract keywords for speed, subject headings for depth. Pair both in the same string with OR so you catch tagged and not-yet-tagged items.
Use library help and trusted guides
Most campus libraries publish quick guides on Boolean logic, field limits, and thesauri. Many offer one-on-one help and workshops. Short sessions save hours later, and librarians can suggest a database you had not tried yet.
Grey literature without the guesswork
Start with known portals and repositories in your area. Add site-limited web searches when needed. Try filetype filters for PDFs or slides. Always capture a copy or a stable link since grey items move more than journal pages.
Craft smarter web searches
When you leave databases, keep your web searches tidy. Quotes hold phrases together. A minus sign drops a term you do not want. site: limits the search to one host. filetype: finds PDFs, PPTs, or spreadsheets. Pair these with strong nouns from your word map, not vague buzzwords.
Web moves that save hours
Use site:.gov, site:.edu, or site:.org for policy or teaching material. Try site:who.int or site:nih.gov when health bodies matter. Add filetype:pdf to find reports. Add a year range with the tool’s date filter. Use quotes for titles when you chase a hard-to-find item from a reference list.
If your terms overlap with pop culture, add a clarifier that belongs to your field.
Evaluate sources with a quick checklist
Ask five plain questions. Does the item match your question? Who wrote it, and are they active in the field? Where did it appear, and does that venue fit your scope? What did they do, and can you follow the methods? How current is it for this topic?
Spot red flags early
Watch for journals that hide fees, missing editor details, or fake metrics. Skim references for breadth and fit. Check whether the abstract claims more than the data support. If the piece uses sweeping claims without clear methods, drop it.
Use a reference manager from day one
Pick a tool that you can learn quickly. Zotero, EndNote, and Mendeley all store citations, PDFs, and notes. Create folders by concept or stage: search results, screen next, keep, and cite. Add tags such as method, region, or sample so you can filter on the fly.
Keep notes that write themselves
Under each source, store a one-line claim, the design, the sample, and the one insight you might cite. Add one line on limits. These short notes turn into paragraphs later without extra digging.
Common pitfalls and easy fixes
Problem: endless results. Fix: tighten concepts with AND, add a field limit, or move to a subject database. Problem: too few results. Fix: expand synonyms with OR, drop a filter, or raise the date ceiling. Problem: off-topic hits. Fix: cut an ambiguous term, add a context word, or exclude a noisy branch with NOT.
Problem: missing full text. Fix: use library links, request an item through document delivery, or search the author’s profile for a posted version. Problem: forgetting where a string worked. Fix: paste each final query and the tool name into your log the moment it runs. Problem: scattered notes. Fix: pick one folder and one naming pattern and stick with it.
Add structure to your screening
If you have a large set, screen in two passes. First pass on titles and abstracts only. Second pass on full text for the items marked yes or maybe. Record the count at each stage. Those numbers help you explain what you read and what you set aside.
| Where | String or steps | Notes |
|---|---|---|
| Database or tool | Final query, filters, fields | Date run, hits, tweaks to try next |
| Citation chasing | Key paper → “Cited by” → new papers | Why each new paper looked useful |
| Grey literature | Site searches, portals, or repositories | Org names, years, and file types |
Put it all together for a strong literature review
Begin with a mapped question. Search a broad index, then a subject database. Build strings with Boolean logic, phrases, truncation, and controlled vocabulary. Chase citations in both directions. Log strings and decisions. Screen with a simple rule. The result is a reading list you can trust and a set of steps you can repeat.
Helpful links: Google Scholar help and the Cochrane Handbook chapter on searching.