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Systematic Reviews

A guide for researchers undertaking a systematic review

Where should you search?

When conducting a systematic review, it is important to search widely for both published and unpublished research, to find all information available on your particular topic.

The information sources you choose will depend on your research topic.

Databases

You will need to search a wide range of subject-specific databases in order to capture the full extent of published journal literature on your topic.

Databases index different sets of journals, and while some are expected to overlap, you will also find unique content in each database.

Most subject areas will have core databases that the majority of systematic reviews use, and additional subject-specific databases depending on the topic.

The library provides access to key databases such as:

 

If you are unsure about the key databases to search for your review:

  • Browse the library's databases by subject in your area of focus
  • Check other systematic reviews in your subject area to see the list of databases they searched
  • Consult a librarian

 

For further reading and guidance, consult the resources below:

Health and medical sciences

 

Social sciences, engineering, business and education areas

Citations and references of key article are an important supplementary source of published literature and will often help you to discover additional studies that have not appeared in the results of your databases searches.

Citation searching can also help you track a particular study over a period of time - allowing you to follow the study through time, to see if they are relevant to your review.

To do this, search for a key article you know of, then use the database's functionality to link to citations and references for that article.

Citation databases include:

For more information, watch the short video below which explains how to do citation searching on Web of Science.
https://www.youtube.com/watch?v=HVq2J1OeANc)

Additionally, visit our Citations, Altmetrics and Researcher Profiles guide

 

Grey literature

Grey literature refers to material produced in non-traditional ways, outside the control of commercial publishers.

Some examples of grey literature include government reports, theses, clinical trials, standards, official documents, and conference proceedings.

 

Why is grey literature important?

Grey literature helps you to form a more complete view of all the evidence around your particular topic. A review can be biased when it fails to report crucial information that may be hidden in some grey literature. It is therefore necessary to include it as part of your systematic review to minimise publication bias.

Grey literature can also be a good source of up-to-date literature for newer areas of research.

 

Tips for finding grey literature:

  • Keep it simple - focus on your key concepts, don't try to run long strings of search terms.
  • Choose key organisations, professional associations, government department websites, and grey literature databases and directories.
  • Find similar systematic reviews in your subject area, and see how they approached their grey literature search.
  • Record where, when, and how you searched each resource.
  •  

For more information on finding and documenting grey literature:

University of Toronto Libraries. (2024). Searching the literature: A guide to comprehensive searching in the health sciences. Gerstein Science Information Centre. https://guides.library.utoronto.ca/c.php?g=577919&p=4123572#s-lg-box-15768802

Wanner, A. (2017, August 29). Grey lit searching for dummies. Expert searching. https://expertsearching.wordpress.com/2017/08/29/grey-lit-searching-for-dummies/

Clinical Trial Registers

Clinical trial registers are databases that store information about ongoing and completed clinical trials.

 

Databases

Many library catalogues and databases also index types of grey literature including conference papers, reports, theses, and government documents.

Most library databases and catalogues allow you to limit search results by publication or document type, which will allow you to narrow your search to grey literature sources.

 

Google

To effectively search for grey literature using Google, we recommend using Google Advanced Search.

Here you can enter your search terms and apply limits in the 'Narrow your results' section.

Consider restricting your search to a site or domain, note that you can only search one domain at a time.

  • .edu or .ac for academic institutions
  • .org for organisations
  • .gov for government sites

Much of the grey literature available on the internet is in PDF document form. You can limit your results by file type:

  • Select 'Adobe Acrobat PDF' to limit to .pdf results
  • OR include filetype:pdf in your search query.
    eg. "Cancer diagnosis after COVID filetype:pdf" would show results for PDF files about cancer diagnosis after COVID.

 

Institutional Repositories

Institutional repositories provide access to digital theses and research papers.

Some resources include:

 

Websites

The internet is a major source of grey literature and is a good starting point to a topic area.

Search or browse the websites of key organisations in your research area. These may include;

  • Government agencies
  • Academic or research institutes
  • Professional associations
  • Advocacy groups

 

Australian websites International websites

Analysis & Policy Observatory

Australian Bureau of Statistics

Australian Institute of Health & Welfare

Australian Indigenous HealthInfoNet

World Health Organization
Reports, data and publications from the WHO

Grey Literature Report
Publications in health services research and public health topics

AHRQ
Agency for healthcare research and quality

MedNar
Medically-focused deep web search engine

BASE
Multidisciplinary scholarly resources by Bielefeld University Library, Germany.

CORE
Open Access research papers

 

Evaluating grey literature

Grey literature is usually not subject to the same peer review process as books, journals, and commercially published literature.

Therefore, it is important to critically evaluate grey literature to ensure it is of a suitable quality to include in your systematic review.

To help you with resource evaluation, you may refer to the AACODS checklist created by Jess Tyndall, Flinders University. The checklist covers:

  • Authority - is the author credible?
  • Accuracy - is information supported by authoritative references? Is it in line with other work on the same topic?
  • Coverage - have limitations been stated clearly?
  • Objectivity - is there any bias?
  • Date - it is best to avoid undated material
  • Significance - is it relevant? Would it have an impact on your research?

 

This scholarly sources checklist from Monash University Library is another useful guide to evaluating sources.

Handsearching

Handsearching is the manual examination of key journals or conference proceedings to identify any further studies of interest by examining  indexes, pages and reference lists of selected documents. 

Handsearching is not required in all situations, but in certain circumstances, such as when looking at older material, it might be important to avoid missing relevant material.

See the Cochrane Training link below for guidance on handsearching:

Cochrane Training (Guide to Handsearching)

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