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 Tennyson AND Memory will return items that contain both terms only:
Tennyson OR Memory returns sources that contain either "Tennyson" or "Memory" separately or both terms together:
Tennyson NOT Memory returns items that contain "Tennyson" but not "Memory":
An important strategy for one to employ when researching phrasal concepts (e.g., "European Union") or conducting known-item searches for titles:
For example, Charge of the Light Brigade (without quotation marks) will search for separately for charge, of, the, light, and brigade.
However, "Charge of the Light Brigade" in quotation marks will search for Tennyson's poem 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 history) AND Tennyson will return results for Tennyson 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.