Unabridged Dictionaries do not necessarily include every word in existence. As a general rule, an unabridged dictionary contains 265,000 or more words. On CD-ROM, see Gale's Quotations . Subject Dictionaries are limited to particular subject or discipline. Subject Encyclopedias provide more detailed coverage than a general encyclopedia, because they are limited to only one subject or discipline.
Directories are lists of people, organizations, etc.
Some directories can be very specialized in their coverage, as well. The information in a yearbook is usually more detailed than that found in an almanac. Statistical Sources are often, but not always, government publications that contain statistical information. Indirect Sources provide a list of citations to locate biographical information about a particular person. Before using any biographical source, check the scope of the work.