Once the search of the databases, etc has been carried out there are a number of techniques available to extract more materials. There are three main ways to do this - snowballing, hand searching and following up reference lists. Each of these methods is described below.
Sometimes it may be appropriate to 'snowball' your search. Another name for this method is citation searching. This involves screening all the articles that cite your included papers (the articles which meet your inclusion criteria after screening). To do this you use the two citation databases - SCOPUS and Web of Science. Use these to search for the titles of each included article in each of the databases, and any listed citing article which meets your inclusion criteria should also be included in the review.
Advice and support on using both databases is available from Library staff, and there are also lots of self help videos available form the vendor sites - SCOPUS (link opens in new window) and Web of Science (link opens in new window).
Image courtesy Martin Deutsh
Hand searching involves looking back through the tables of contents of key journals, conference proceedings, or lists of conference presentations for your systematic review topic. Once you have identified key journals, plan how many years back you will look — this will need to be done consistently across all journals that you hand search. You may also alternatively use Scopus and Web of Science to carry out this task.
Journal TOCs (link opens in a new window) is a service which emails subscribers the tables of contents of any journals selected. This means you can keep track of future issues of the journal(s) without needing to remember to check them. You will need to sign up with an email address and password.
After you have screened all the papers identified by your database and grey literature searches, and agreed on which will be included in the review, you can check through their reference lists. Any articles in their reference lists which meet your inclusion criteria should also be included in the review. Please note: this should only be done for the included papers (those which meet your inclusion criteria after screening), not every article you find in your database search.
For any assistance/advice required please contact the Library Team at: hhsl@uhi.ac.uk