beaver AND duck = platypus
source: http://i.imgur.com/8BFAq.png
To expand your search results, consider searching in general and multidisciplinary databases or search for multiple databases with the same platform.
For example, when you search the Social Work Abstracts database, click on the "Choose Databases" link. This will allow us to search all or selected EBSCOhost databases in tandem (see image). Duplicate records are usually removed. The drawback is that subject headings cannot be used when using this tactic.
If you found an "ideal" article, here are two ways to expand your search Web of Science database
Retrieve the "ideal" article on the Web of Science database or in Google Scholar. Then, examine the record for articles that cite your "ideal" article (that is, click on the "Times Cited" articles on Web of Science).
This citing reference searching is a quick and efficient way to find more related and newer articles.
Look at the references (e.g. "Cited References" or bibliography of the article) in your "ideal" article as these articles may be related in some fashion; and will be older than your "ideal" article.