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Systematic Reviews - Research Guide

Where to search

Where to search?

Searches for systematic reviews should be as extensive as possible, and should cover multiple databases, grey literature and other sources.

The literature search for a systematic review should:

  • answer a clearly defined clinical question
  • use a search strategy that is comprehensive, explicit and sufficiently detailed that it could reproduced using the same methodology, with exactly the same results, or updated at a later time
  • be performed using all relevant databases
  • include all available research including published research, grey literature and unpublished data.


Choosing databases to search

You will need to search multiple databases for a comprehensive search. At least two, but generally no more than five, is recommended. 

Databases should be selected with consideration of the topics covered and types of material indexed. When choosing each database, you might consider:

  • whether the database includes topics relevant to your review question
  • the types of materials indexed.

For systematic reviews in health topics, it is recommended to search MEDLINE (via Ovid or PubMed). If the type of evidence required to answer the question includes RCTs, then CENTRAL should also be searched.

Additional subject-specific and region-specific databases should be selected based on review topic or context.

For example, for a nursing-related review additional databases could include CINAHL, Emcare, and/or Health Collection (Informit).

A multidisciplinary database such as Web of Science could be searched as well; this database indexes a diverse range of topics and increases search sensitivity.

Types of databases:

  • Subject-specific. For example:   
    • Business Sources Complete - organisational psychology
    • ERIC - education & developmental psychology
    • MEDLINE, CINAHL - health topics
    • PsycINFO - psychology topics.
  • Multidisciplinary. For example:
    • Scopus
    • Web of Science.
  • Citation databases. For example:
    • Scopus
    • Web of Science.
  • Systematic review / EBP databases. For example:
    • Cochrane Library
    • Joanna Briggs Institute EBP Database.

Database vs platform

It is important to know the difference between a database and a platform if you are undertaking a systematic review. 

Databases are organised, indexed collections of records with descriptive information, which facilitate searching. Bibliographic references contained in a bibliographic database can include articles, books, conference proceedings, etc. Databases vary in scope, subject focus, publishers and journals indexed. A well-documented database search that is reproducible and transparent is a fundamental component of a systematic review search. CINAHL, PsycINFO and Web of Science are examples of databases.

Platforms are search interfaces that provide access to databases. Some platforms host multiple databases and allow searching of individual or multiple databases. However, for a systematic review you should always search databases individually.  Some databases can be accessed through multiple platforms; for example, the database MEDLINE can be searched through the platforms Ovid, Web of Science, and PubMed. Coverage may differ depending on the platform used to access the database. 

When reporting your search in your systematic review, you should name each individual database searched and the platform used (PRISMA-S).

Database (Platform)


BIOSIS Citation Index 

Indexes journals, reviews, conferences, patents and books in the life and biomedical sciences.

CAB Abstracts

The most comprehensive database for veterinary and animal science and agriculture.

CINAHL Ultimate

Covers nursing and allied health topics including audiology, nutrition and dietetics, occupational therapy, physical therapy, respiratory therapy, speech-language therapy, counselling, mental health and consumer health. CINAHL User Guide

Health & Medical Complete (ProQuest)

This database provides broad coverage of clinical and biomedical literature, and provides access to over 900 full text biomedicine journals.

Health Collection (Informit)

A full text and indexing database of over 100 Australian and New Zealand health sciences resources.

The link will take you to the main Informit platform - select the database, Health Collection.


The United States National Library of Medicine's premier bibliographic database for medicine, nursing, veterinary medicine, allied health, and the pre-clinical sciences.
Ovid allows for keyword proximity searching. For example, (cognitive ADJ3 therapy) will find the words cognitive and therapy within TWO words of each other in either direction, and many more papers than a search for the specific phrase “cognitive therapy” would retrieve. Papers which include the terms 'cognitive behavior therapy' or 'cognitive behaviour therapy' would be included in search results for example.

MEDLINE (Web of Science)

The United States National Library of Medicine's premier bibliographic database for medicine, nursing, veterinary medicine, allied health, and the pre-clinical sciences. MEDLINE User Guide


Multidisciplinary collection of journals, magazines and theses, which includes many business, management and economics resources.


Indexes and abstracts over 1300 journals in more than 25 languages. Includes book chapters, books, technical reports and citations to dissertations. Covers professional and academic literature in the field of psychology and psychological aspects of related disciplines.


Includes over 18 million citations from MEDLINE and other life science journals. Subject coverage includes all areas of medicine and related disciplines. Links to full text journals are also available in PubMed Central as well as links to a series of molecular and genome databases.


A multidisciplinary database which is very strong in the sciences and has many useful search features. It includes all of the journals indexed in MEDLINE.

Web of Science Core Collection

Provides access to all of the Web of Science citation indexes: Science Citation Index Expanded, Social Sciences Citation Index and Arts & Humanities Citation Index.

All Databases

Browse by subject or category.

Database name


Campbell Collaboration

The Campbell Collaboration is an international research network that produces systematic reviews of the effects of social interventions in Crime & Justice, Education, International Development and Social Welfare

Centre for Reviews and Dissemination (University of York) 

The Database of Abstracts of Reviews of Effects (DARE) and the NHS Economic Evaluation Database (NHS EED) provide access to:

  • over 35,000 quality assessed systematic reviews of health and social care interventions,
  • summaries of all Cochrane systematic reviews and protocols up to March 2015,
  • over 17,000 economic evaluations of health and social care interventions

Cochrane Library

Indexes journals, reviews, conferences, patents and books in the biological and biomedical sciences

Joanna Briggs Institute EBP Database

Provides resources for evidence-based research including best practice information sheets, systematic reviews and electronic journals and conference papers. Consumer health-care information is also available

PubMed Clinical Queries

Includes systematic reviews and reviews of clinical trials

Grey literature

The term grey literature "is usually understood to mean literature that is not formally published in sources such as books or journal articles" (Lefebvre, Manheimer, & Glanville, 2008, p. 106).

Grey literature may include multiple types of document produced on all levels of government and by academics, businesses and organisations  in electronic and print formats where publishing is not the primary activity of the producing body. (Greynet, 2015.)    

Examples are:

  • clinical trials
  • conference proceedings
  • economic data
  • ephemera
  • geospatial data
  • infographics
  • interviews
  • maps
  • meeting notes or minutes
  • newsletters, emails, blogs and other social networking sites (examples of community based grey literature)
  • official documents
  • patents
  • personal memoirs
  • policy statements
  • posters
  • practice guidelines
  • reports (reports of government and research institutes are generally freely available on the internet)
  • standards
  • technical specifications and standards
  • technical and commercial documentation
  • theses
  • translations

There may also be grey literature that is specifically relevant to your discipline.
Practice guidelines are highly relevant to nursing and health professions, working papers are used in the social sciences (particularly economics) and patents are important to engineering.

A systematic review conducted in 2008 by members of the Cochrane methodologies team found that  the results from grey literature often have a significant effect on the outcome of a review, as they often report more negative or inconclusive data than published journal articles (Hopewell et al., 2008). 
As such, it is important to treat grey literature as another potential source of studies for inclusion while noting that it is usually not subject to peer review and must be evaluated accordingly.


1. Alberani, V., De Castro Pietrangeli, P. & Mazza, A.M.  (1990).  The use of grey literature in health sciences: A preliminary survey.  Bulletin of the Medical Library Association, 78 (4) : 358-363. Retrieved from 
2. GreyNet International (2015). Retrieved from
3. Lefebvre C, Manheimer E, Glanville J. (2008). Searching for studies. In: J.P.T. Higgins & S. Green (Eds.), Cochrane handbook for systematic reviews of interventions. Chichester: Wiley-Blackwell.
4. Hopewell S, McDonald S, Clarke M, & Egger M. (2007).
Grey literature in meta-analyses of randomized trials of health care interventions. The Cochrane Library.  doi: 10.1002/14651858.MR000010.pub3

Australian Government Information

Government departments (State and Commonwealth) can be found using Google. Some useful sites are listed below:

International Sources


University repositories, such as the Murdoch Research Portal, can be used to locate theses, research papers and data if they have been made available.
Information about locating theses and dissertations can be found in the Murdoch Library Theses Guide.


Databases That Include Grey Literature

Use the Document Type/Source Type/ Publication Type filters to search for specific formats of grey literature.

In addition to the sources listed above, internet searching can locate other useful sources:

  • Remember there are two spellings and search for (gray OR grey) literature when searching for grey literature in general
  • Find and search the online catalogues of large libraries
  • Search for the host sites of conferences and academic associations for conference papers or proceedings
  • To find conference papers in Web of Science, enter your search terms, and on the results page see 'Document Types' in the 'Refine your results' panel and select 'Proceeding Paper'
  • Try restricting your search to the .org and/or .gov domains
Grey literature search words

When developing a search strategy, specify what type of content is to appear in search results.

Example search words to include:


thesis OR dissertation OR doctorate

government AND (report OR strategy)

"working paper" OR "white paper" OR "green paper"​

(conference OR seminar OR symposium OR workshop) AND (paper OR proceedings)

Internet searches can include file types:

ofiletype:xls OR xlsx

You should evaluate grey literature in the same way as other document types that are included in your research.

  • Currency - does the date fit with the research purpose? It is best to leave the data if a date cannot be found.
  • Relevance - is it significant? Does it enrich or have an impact on the research? Have limitations been imposed and are these stated clearly?
  • Authority - has the report come from a reputable institution or organisation?
  • Accuracy -  is it supported by documented and authoritative references? Is there a clearly stated methodology?
  • Bias - is the source objective? Look carefully at commercial or political sources for funding bias. Studies with more 'positive' results - those which show a definite effect for an intervention - are three times more likely to be published than ones which show little or no positive effect.

The AACODS checklist created by Flinders University is also a useful tool for evaluation and critical appraisal of grey literature.