You are probably fairly comfortable doing basic searches already, but they can take your research only so far. To make bigger strides on your research and find more targeted results, try out some advanced searches. Most library catalogs, databases, and Web search sites provide an advanced search page. These pages allow you to focus your searches in powerful ways using Boolean operators (which are used to search for all, some, or none of the words or phrases in a search box) and search limits (such as publication date and document characteristics).
Focus searches with Boolean operators. Boolean operators let you focus a search by specifying whether keywords or phrases can, must, or must not appear in the results. Some Boolean operators also allow you to search for keywords or phrases that appear next to, before or after, or within a certain distance from one another in a document. Here is a list of commonly used Boolean operators and their functions.
| Boolean Operator | Function | Example |
|---|---|---|
| AND/+ (plus) | Finds sources that include both search terms (either keywords or phrases) | hydrogen AND economy |
| OR | Finds sources that include either search term | energy OR power |
| NOT/– | Finds sources that include one search term but not the other | gasoline NOT oil |
| ADJ (adjacent) | Finds sources in which the search terms appear next to each other | fuel ADJ cells |
| NEAR | Finds sources in which the search terms appear within a specified number of words from each other | alternative NEAR energy |
| BEFORE | Finds sources in which search terms appear in a particular order | clean BEFORE power |
| Parentheses ( ) | Parentheses are used to group search terms and Boolean operators | hydrogen AND (fuel OR energy) AND (economy NOT economics) |
Limit searches. Search limits allow you to limit your searches to documents that have particular characteristics, such as publication date and document type. Although the specific limits that are available in an advanced search form vary across databases, library catalogs, and Web search sites, common limits include publication date (or, in the case of Web pages, the date on which a page was last updated), type of document, and the availability of full text (for databases).