APA

National Library of Medicine, . (1994). National Library of Medicine classification. Bethesda, Maryland: U.S. Dept. of Health and Human Services, Public Health Service, National Institutes of Health, National Library of Medicine.

Chicago

National Library of Medicine, . 1994. National Library of Medicine classification. Bethesda, Maryland: U.S. Dept. of Health and Human Services, Public Health Service, National Institutes of Health, National Library of Medicine.

Harvard

National Library of Medicine, . (1994). National Library of Medicine classification. Bethesda, Maryland: U.S. Dept. of Health and Human Services, Public Health Service, National Institutes of Health, National Library of Medicine.

MLA

National Library of Medicine, . National Library of Medicine classification. Bethesda, Maryland: U.S. Dept. of Health and Human Services, Public Health Service, National Institutes of Health, National Library of Medicine. 1994.