The Library of Congress Classification (LCC) was developed in the late 19th and early 20th centuries to organize and arrange the book collections of the Library of Congress. The system was widely adopted by other libraries as well, especially large academic libraries in the US.
The system divides all knowledge into 21 basic classes, each identified by a single letter of the alphabet, most of which are further divided into more specific subclasses, identified by two-letter, or occasionally three-letter, combinations. R represents the class for medicine.
To see the 21 basic classes, click here
The National Library of Medicine Classification covers the field of medicine and related sciences, utilizing schedules QS-QZ and W-WZ, permanently excluded from the Library of Congress (LC) Classification schedules. The various schedules of the LC Classification supplement the NLM Classification for subjects bordering on medicine and for general reference materials. The LC schedules for Human Anatomy (QM), Microbiology (QR) and Medicine (R) are not used at all by the National Library of Medicine since they overlap the NLM Classification.
To see the NLM Classification scheme, click here.
National Library of Medicine:
MeSH, an acronym for Medical Subject Headings, is the U.S. National Library of Medicine's controlled vocabulary used for indexing articles for MEDLINE/PubMed. MeSH terminology provides a consistent way to retrieve information that may use different terminology for the same concepts.
Library of Congress:
LCSH has been actively maintained since 1898 to catalog materials held at the Library of Congress.
LOC Authorities: Using Library of Congress Authorities, you can browse and view authority headings for Subject, Name, Title and Name/Title combinations; and download authority records in MARC format for use in a local library system.