The Art and Architecture Thesaurus Browser
- "The Art & Architecture Thesaurus is a controlled vocabulary that can be used to improve access to cultural heritage information in the global networked environment. ... The AAT is a comprehensive vocabulary of nearly 120,000 terms for describing
- http://www.getty.edu/research/conducting_research/vocabularies/aat/

Physics and Astronomy Classification Scheme (PACS)
- A subject-specific, hierarchical classification scheme prepared by the American Institute of Physics (AIP) in collaboration with certain other members of the International Council on Scientific and Technical Information (ICSTI). The site provides the 19
- http://www.aip.org/pacs/

NLM (National Library of Medicine) Classification
- Covers the field of medicine and related sciences. Designed to enable integration into an LCC environment, it utilizes schedules QS-QZ and W-WZ, permanently excluded from the LC Classification Schedules.
- http://wwwcf.nlm.nih.gov/class/

Alpha-Numeric System for Classification of Recordings (ANSCR)
- Outlines the major categories of the ANSCR classifiction system and provides a brief explanation of the call number composition. ANSCR is the system used by many public and academic libraries for the arrangement of sound recordings.
- http://www.calstatela.edu/library/guides/anscr_class.htm

Preservation Descriptors & Classification Schemes
- Classification schema related to preservation, drawn from a number of sources, including LISA, ERIC, Art Index, Applied Science and Technology Index, and seven others.
- http://palimpsest.stanford.edu/lex/kessecls/

Mathematical Subject Classification
- A detailed outline of the classification scheme used by the American Mathematical Society for papers on mathematical subjects.
- http://www.ams.org/msc/

Medical Subject Headings
- The Medical Subject Headings comprise the National Library of Medicine's controlled vocabulary used for indexing articles, for cataloging books and other holdings, and for searching MeSH-indexed databases, including MEDLINE. This site includes Changes in
- http://www.nlm.nih.gov/mesh/meshhome.html