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.
Some works are current, some are retrospective, and it saves time to know which is which.
Maps often have a larger scale and include more detail than atlas maps do. Historical atlases assist in the study of boundary changes, military campaigns, and early exploration. See Books in Print . Subject bibliographies list works on a specified subject. Periodical bibliographies list the titles of periodicals, magazines, and journals.