DIMDI: Klassifikationen im Gesundheitswesen
http://www.dimdi.de/germ/klassi/fr-klassi.htm

Medical Subject Headings - MeSH
http://www.nlm.nih.gov/mesh/meshhome.html

Unified Medical Language System - UMLS
http://www.nlm.nih.gov/research/umls/umlsmain.html

Glossary of Managed Care Terminology
http://www.texmed.org/lis/gth/reference_shelf.asp