LC also acquires materials at the basic information level to serve other government agencies and the general public. LC has a strong basic collection of U.S. copyrighted works on pets and pet care. In addition, English language works on wildlife in captivity and wildlife rehabilitation are collected to complement the Library's collection strength in biodiversity. Older material is retained for historical research. It is intended to include all important reference works and a wide selection of specialized monographs, as well as a very extensive collection of journals and major indexing and abstracting services in the field.
Older material is retained for historical research.
It includes a wide range of basic monographs, complete collections of the works of more important writers, selections from the works of secondary writers, a selection of representative journals and the reference tools and fundamental bibliographical apparatus pertaining to the subject. It may include dictionaries, encyclopedias, selected textbooks, surveys, histories, directories, bibliographies, handbooks and a few major periodicals, in the minimum number that will serve the purpose. A basic information collection is not sufficiently intensive to support any courses or independent study in the area involved. Instead of following the five levels defined by RLG, NLM stated that it would attempt to collect comprehensively biomedical aspects of any subject. NLM recognizes that while it is possible to assemble a collection which addresses all topics in biomedicine, it is impossible even for a national library to gather a complete, worldwide collection of all biomedical materials in all formats.