Optionally, narrow the topic by combining it with other subject concepts . Proximity is also called adjacency. This technique finds one word within several words of another. Use the database's help files to see how these features are implemented. Some subjects are so large that retrieving all of the relevant literature would be impossible.
Most databases can limit search results by categories.
Date ranges, languages, and publication types are common, but others that suit specific disciplines are possible. Good Web metafinders use the same techniques, applying them to URLs, titles, documents, etc., instead of language, date, or format. The right answer is always 50 references. Searches should be constructed so that the results set is small enough to obtain and review the results in a reasonable time frame, but large enough to consider a different approach if the field is too narrow. If you used the Venn Diagram approach, add more groups or more synonyms in each group.