Reference sources, such as encyclopedias, dictionaries, handbooks, provide short overviews that can offer background information, a source for keywords or terms to search library databaases, and sometimes references to other sources. Some are online and others are in a physical format.
The links go to the Library Catalog page for the title. For online books, click "View Online." For resources from Oxford, there are options to "Search in this book" on the left side of page and to search "Oxford Academic" (across all book titles) in the upper-right header of page. For physical books, note the location and call number and go the library location.