Phrase Searching (continued)

• Using search tags, quotes, hypenation or truncation instructs PubMed to bypass automatic term mapping. Instead PubMed looks for the phrase in its Index of searchable terms. If the phrase is in the Index, PubMed will retrieve citations that contain the phrase.
• PubMed may fail to find a phrase because it is not in the Index.
• Your phrase may actually appear in citation and abstract data, but may not be in the Index. If this is the case, the double quotes are ignored and the phrase is processed using Automatic Term Mapping.

Note: Try your search with and without quotes, hypenation and truncation and compare your results.