Your search needs to be as exhaustive as possible, and include published and unpublished sources.
Use more than one source, and don't rely on Google or Google Scholar. You can construct much more structured searches on bibliographic databases such as Medline and PsycINFO. Some databases use a controlled vocabulary (subject headings) which can help ensure you capture all the relevant studies, for example, Medline uses MeSH (Medical Subject Headings).
Your Academic Liaison Librarian will be happy to help you identify possible places to search.
When you're just starting out you might want to do a quick scoping search to evaluate the amount of literature on a topic. To do this you could start with the Library's discovery service Summon. This searches across all our subscribed online journals, you can also check a box to extend your search beyond the subscribed resources.
You should also do scoping searches to identify relevant databases (see below). These preliminary searches will also help you identify relevant keywords to use.
Start with identifying the key databases covering your field by taking a look at the e-resources section on appropriate subject guide(s). Your Academic Liaison Librarian can also advise on the best ones to search.
When looking at other systematic reviews you might identify useful databases which are not available at Reading (e.g. EMBASE). It may be possible to access these by visiting another library. For instance the British Library offers access to a range of databases however there are restrictions on downloading from these databases which will make adding the references to a reference manager very difficult. You will also need to register as a reader with them.
If you are unsure which databases to use, try looking at existing reviews in the same field for details of which databases they searched (see the box on the left for some sources).
You may also wish to extend your search beyond the mainstream databases to ensure global coverage. The University of Leeds Library has put together a list of databases which may help:
Your Academic Liaison Librarian can offer further advice on accessing databases which are not part of our collection.
Once you have identified the key journals you may want to browse through their contents, or do a keyword search directly on the journal site, to make sure you haven't missed anything. Use BrowZine to access journals covered by Library subscriptions.
To supplement keyword searching for a comprehensive review, or for topics which are difficult to frame in a keyword search, take a look at the list of references at the end of any key articles to identify other possible studies. Some databases, such as Web of Science, Scopus and Google Scholar, allow you to track citations forward and identify papers that have cited a key paper since it was published. This gives an alternative way of identifying relevant studies which may not be retrieved by your keyword search.
In addition to identifying published resources you will need a strategy for finding grey literature. This is usually research material that is not available via the usual published sources. This can include:
These can be identified by running internet searches, and consulting key websites of relevant organisations.