National Center for Health Statistics (NCHS) descriptions and downloadable files for International Classification of Diseases (ICD) and International Classification of Diseases, Clinical Modification (ICD-CM)
International Health Terminology Standards Development Organisation (IHTSDO) administers the rights to SNOMED CT and other health terminologies and related standards
National Library of Medicine's Unified Medical Language facilitates the development of computer systems that behave as if they "understand" the meaning of biomedical and health language