A computerized biomedical bibliographic storage and retrieval system operated by the NATIONAL LIBRARY OF medicine. medlars stands for Medical literature Analysis and Retrieval System, which was first introduced in 1964 and evolved into an online system in 1971 called medline (medlars Online). As other online databases were developed, medlars became the name of the entire NLM information system while medline became the name of the premier database. medlars was used to produce the former printed Cumulated Index Medicus, and the printed monthly Index Medicus, until that publication ceased in December 2004.