Key points at a glance
- Break your question into a few central concepts.
- Join synonyms with OR and different concepts with AND.
- Check the syntax and results separately in each database.
What is a literature search string?
A search string is a recorded combination of terms and operators. It translates your research question into a query a database can process. Instead of entering your complete thesis title, you identify the central concepts and the different ways researchers describe them.
Start with a vocabulary list for each concept. Include established terminology, common abbreviations and relevant language variants. Separate genuine synonyms from neighbouring topics. Otherwise, a seemingly helpful extra term can quietly change the question your search addresses.
Combine concept blocks with AND and OR
Use OR for alternative terms within a concept block and AND to connect different concepts. Parentheses show which terms belong together. The University of Leeds explains this logic and cautions that NOT can remove relevant literature as well as unwanted results.
Original example: A starting query about digital learning and examination anxiety might be ("online learning" OR "digital learning") AND ("test anxiety" OR "exam anxiety"). This is an initial draft, not a validated strategy. Add terminology from relevant papers and confirm that your database supports the syntax.
Check the syntax and test the query
Quotation marks, wildcards and field codes do not work identically across platforms. Read the database help before using truncation or restricting a query to titles and abstracts. Copying a string from another platform without adapting it can produce misleading results.
Test your draft against a few relevant publications you already know. If they are absent, inspect their terminology, metadata and database coverage first. Change one component at a time and record whether it adds useful sources or mainly irrelevant material.
A large result set is not automatically a problem, and a small one is not automatically precise. Inspect a sample: does it address your subject, population and methods? Use this evidence when deciding whether to add another concept block or apply a filter.
Record the search you actually ran
Save the database, search date, exact query, searched fields, filters and result count together. Keep a short record of meaningful revisions. A polished query reconstructed afterwards may not describe how you actually found the literature.
Export the results to your reference manager and remove duplicates using a documented process. The search string explains discovery; it does not establish that every result deserves inclusion. Relevance and source quality still need separate assessment.
Final submission context
Formal details can feel like a separate writing task, but they matter just as much for a printed submission. Anything missing, misplaced or inconsistently formatted in the document will also appear in the bound copy.
Use this guide together with your cover page, table of contents, page numbers, source notes and appendices. Prepare the final PDF for printing and binding only after the complete file has been checked.
Practical check before PDF export
- Do headings, chapter structure and page numbers match?
- Are sources, figures and tables included completely?
- Are required elements such as declarations, appendices or the cover page included where required?
- Did you open and check the final PDF after exporting it?
Checklist
- Separate the main concepts.
- Collect synonyms and language variants.
- Test operators and parentheses.
- Verify platform-specific syntax.
- Save the query, date, filters and result count.
Common mistakes
- Using the thesis title as the only query.
- Removing relevant studies through an unchecked NOT clause.
- Treating result count as proof of quality or completeness.
Print and bind your finished thesis
Once you have checked the content and final PDF, configure the printed copies to match your submission requirements.
Configure printing and bindingRelated content
Explore related guidance on thesis structure, sources, formatting and final submission.
Frequently asked questions
How many search terms should I include?
There is no fixed number. Cover your main concepts and relevant synonyms. Too many mandatory AND blocks can exclude suitable studies when a concept is absent from their searchable metadata.
Can I use the same string in Google Scholar?
Not necessarily. Transfer the search logic first, then adapt the syntax to the platform. Record the exact query you actually used in each system.
Should the complete string go in an appendix?
A complete query is useful when you need to document literature selection. Its location in the methods chapter, appendix or search log depends on your project and university requirements.