A product of the National Library of Medicine for the arrangement of library materials in the field of medicine and related sciences used internationally. The NLM Classification is updated twice a year with the winter edition published in January and the summer edition published in August. Publication of printed editions ceased with the 5th revised edition, 1999. Beginning with the 2006 edition, the NLM Classification is also available in PDF (Portable Document Format) at https://www.nlm.nih.gov/class/terms_cond.html

The National Library of Medicine's (NLM) Digital Collections offers a search-based Web service that provides access to the Dublin Core metadata and full-text OCR of every resource in the repository in XML format. Developers can use the Web service to build applications that query and link to these resources.

The List of Serials Indexed for Online Users (LSIOU) provides bibliographic information for all journals whose articles were ever indexed over time with the MeSH® vocabulary and cited in MEDLINE®, the backbone of the NLM PubMed® database. It includes titles that ceased publication, changed titles, or are no longer indexed. More detailed bibliographic data and information about indexing coverage for serials cited in MEDLINE/PubMed can be found in LocatorPlus Catalog®, the NLM online catalog, and the NLM Catalog, an Entrez database.

IndexCat provides access to the digitized version of the printed Index-Catalogue of the Library of the Surgeon General's Office; eTK for medieval Latin texts; and eVK2 for medieval English texts; along with links to other selected NLM resources.

The collections described in this Directory database provide research and reference services to scholars interested in the history of the health sciences. Some of the subjects include: dentistry, veterinary medicine, nursing, biomedical sciences, military medicine, and pharmacy. While the Directory is by no means exhaustive, it serves to draw attention to the depth and variety of history of medicine collections available to researchers. In the future, we expect that more institutions will wish to be included.

A MARC-based catalog, the LocatorPlus Catalog provides access to NLM bibliographic data for journals, books, audiovisuals, computer software, electronic resources and other materials.

LinkOut is a service that allows you to link directly from PubMed and other NCBI databases to a wide range of information and services beyond the NCBI systems. LinkOut aims to facilitate access to relevant online resources in order to extend, clarify, and supplement information found in NCBI databases.

Third parties can link directly from PubMed and other Entrez database records to relevant Web-accessible resources beyond the Entrez system. Includes full-text publications, biological databases, consumer health information and research tools.