The National Library of Medicine (NLM) is part of the National Institutes of Health and maintains a vast collection of biomedical resources. It produces electronic information resources on health topics that are searched billions of times annually. The NLM Catalog provides bibliographic records for over 1.4 million resources and links to related records in PubMed and PubMed Central. It can be searched to find books, journals, and other materials available through the NLM.