Licensing NLM Bibliographic Products
NLM bibliographic records are available in either the MARC 21 communications format or in XML format on a subscription basis. NLM currently offers three MARC 21 bibliographic products: Catfile, CatfilePlus, and Serfile. CatfilePlus and Serfile are also available in XML. See Leasing Data from the National Library of Medicine or contact firstname.lastname@example.org for more information.