The large number of citations in many catalogs and databases requires one to limit otherwise broad or general searches in order to retrieve a manageable and pertinent number of results. Conversely, overly narrow search terms can return too few results. One way of solving both problems is to use Boolean operators (AND, OR, NOT), which allow one to limit or expand searches depending on his or her needs.
For example, a search for Resnais AND Holocaust will return items that contain both "Resnais" and "Holocaust":
Resnais OR Holocaust returns items that contain either "Resnais" or "Holocaust" or both:
Resnais NOT Holocaust returns items that contain "Resnais" but not "Holocaust":
An important strategy for one to employ when researching phrasal concepts (e.g., "European Union") or conducting known-item searches for titles:
For example, Hiroshima Mon Amour will search for Hiroshima AND Mon AND Amour.
However, "Hiroshima Mon Amour" in quotation marks will search for Resnais' film of the same name.
Nested Searching:When pairing two or more keywords with another keyword, it is helpful to "nest" the former terms within a larger Boolean search.
For example, (memory OR nostalgia) AND Resnais will return results for Resnais and any one (or both) of the parenthetical terms.
(Many catalogs or databases will have an "advanced search" option, which provides multiple search bars to facilitate nested searching.)
Truncation and Wildcards:
Most catalogs and databases enable users to search variations of keywords by using truncation (*) or wildcard (e.g., ?, $, !) symbols.
For example, one could search for politic* to find poltic, politics, political, politicking, and so on.
Wildcard searching works similarly: a search for t??th will return results for teeth, tooth, tenth, and so on.