Skip to Content
United States National Library of Medicine National Institutes of Health

FAQ
MEDLINE Citations Prior to 1966

Question: Why am I retrieving MEDLINE citations with publication dates prior to 1966 when OLDMEDLINE currently covers citations prior to 1966?
Answer:
- Although MEDLINE contains citations published mostly from 1966 to the present, it also includes about 109,000 citations from the years 1963-1965 because of the time lapse between the publication of these issues and their actual receipt and completion of indexing by NLM. The year 1966, which is often used to describe the start of MEDLINE, actually refers to the indexing year, not the year of publication. There is no overlap between the pre-1966 citations in MEDLINE and those in OLDMEDLINE.

Return to the top | Return to the list of FAQs
http://www.nlm.nih.gov/services/oldmed.html

Last updated: 03 November 2004
First published: 23 April 2003
Metadata| Permanence level: Permanence Not Guaranteed