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University Library Zurich

Systematic Literature Search

In a standard literature search, relevant hits are retrieved with a search query that is as precise as possible. The systematic literature search, on the other hand, should be so broad that all potentially interesting literature on a topic is retrieved. The art here is to phrase the search terms in an appropriately broad way, without getting too many non-relevant hits.

1. Formulate the most important aspects based on your question

A systematic search begins with well-structured preparation: each scientific question can be broken down into individual aspects. For each aspect / concept it is checked if thesaurus terms (subject headings) are available and which synonyms / expressions have to be searched. Thus, a search string is created for each concept.

When searching systematically, one must not limit oneself to the focused search with subject headings, but must always supplement this with a free text search. To keep the relevance reasonably high, the phrase search is a good choice. However, this method can prove to be too restrictive.



Proximity operators can be used to enforce proximity in a search with multiple terms, which increases the hit relevance considerably compared to a simple AND operation.

Proximity operators are available in many large databases:

Database/Provider Order of Appearance


  open fixed  
Cochrane Library NEAR/n NEXT/n n
Medline (EBSCOhost) Nn Wn n
Medline (Ovid) adjn n.a. n
Medline (Proquest) NEAR/n or N/n PRE/n or P/n n-1
PubMed [Title/Abstract:~3] n.a. n
Scopus W/n PRE/n n
Web of Science NEAR/n n.a. n



3. Work with a Word template

Database-specific codes can be replaced with Find & Replace commands in a Word template. Subject headings are also database-specific: in each thesaurus (=heading catalog) it must be determined anew whether suitable terms are available. If the strategy is transferred to a database without heading search (e.g. Web of Science), the headings are simply omitted and only the free text search will be applied.



4. Document your search history and system meticulously

It should be possible to repeat a systematic search at any time. Therefore, a precise description and documentation of the employed search strategy are essential. Most of the time it is not possible to closely document a search query with words alone. Supplement the description of the search in the methodology section of your paper/research with detailed documentation of the search strategy for at least one database in the appendix.

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Summer School on the Systematic Review of Animal Research

The CAMARADES Zurich/STRIDE-lab is inviting you to join the Summer School on the Systematic Review of Animal Research from August 28th to 31st, 2023 in Zurich! Discover how systematic reviews can help you navigate the expanding field of biomedical literature and conduct reproducible and evidence-based research. More information and registration.