The United States National Library of Medicine (NLM), operated by the United States federal government, is the world's largest medical library.Located in Bethesda, Maryland, the NLM is an institute within the National Institutes of Health. Its collections include more than seven million books, journals, technical reports, manuscripts, microfilms, photographs, and images on medicine and related sciences, including some of the world's oldest and rarest works. The current director of the NLM is Patricia Flatley Brennan. Source: Wikipedia (en)