Dictionaries and encyclopedias are examples of reference sources. You can use dictionaries to find definitions and encyclopedias to find background information.
The New Palgrave dictionary of economics online gives cross searchable access to the full text of the print 2008 (2nd) edition, as well as the 1987 (1st) edition. In addition there are quarterly additions and updates. The entries can also be browsed, alphabetically or by topic.
