MeSH is the National Library of Medicine's controlled vocabulary thesaurus. It consists of sets of terms arranged in a hierarchical structure that permits searching at various levels of specificity. The MeSH vocabulary is organized into a series of trees.
The Indexing Manual provides discussion on all aspects of indexing at NLM. The Indexing Manual is provided to all new indexers and is available online. The online version contains a search feature.
Technical Memoranda are updates to the Indexing Manual that provide further clarification of a specific issue or address an immediate need. Technical Memoranda are distributed online and on paper at the NLM.
Indexers may use reference materials such as Dorland’s Medical Dictionary or Bergey’s Manual of Systematic Bacteriology. These references are available to indexers onsite at NLM.