Normally, a general heading which comprehends the specific primary heading (i.e., when they are in the class/member or whole/part relationship, e.g., Mathematics and Algebra) is not assigned as an additional heading to a work dealing only with the specific subject. In other words, there is generally no generic posting in the LC subject cataloging system. However, exceptions are made for certain categories of works where "doubling," i.e., assigning bilevel (general and specific) headings to the same work, is considered helpful. An example of such exceptions is biographies of individual persons. Bilevel headings are also assigned if the work deals with the general topic as well as the specific topic or a specific aspect (e.g., place or time) of the general topic.

22.1 Reference

See also:

22.0 Specific (co-extensive) entry