Skip to main content
U.S. flag

An official website of the United States government

Official websites use .gov
A .gov website belongs to an official government organization in the United States.

Secure .gov websites use HTTPS
A lock ( ) or https:// means you’ve safely connected to the .gov website. Share sensitive information only on official, secure websites.

Skip to main content
National Library of Medicine logo

Classification 2025 Summer Edition

Worldwide source of medical classification resources

Class Index

non-alpha A B C D E F G H I J K L M N O P Q R S T U V W X Y Z
Of subjects represented in NLM's classification, appropriate classification number preceded by the letter Z
Of other subjects, LC's Z schedule
See also Abstracts
See also Bibliography