Since December of 1996, the National Library of Medicine link removed (NLM) has been adding to PubMed link removed, citations to articles published before 1966, the traditional cut-off date for MEDLINE link removed searches. These database records come from a number of different sources and date from a time when indexing rules and procedures were different so a different strategy needs to be used when extending your search back to this older material. This material is grouped together under the name OLDMEDLINE link removed.

Undoubtedly the most important thing to keep in mind is not to use the MeSH link removed Database when inputting your search. Although there are descriptors or keywords assigned to each record in the database, they do not appear in the MeSH descriptor field of the record and the descriptors used are what were used in the print indexes in the 1950s and early 1960s. They have not been updated, standardized, or "maintained" the way NLM has done since 1966.

Also, the hierarchical structure that allows us to "explode" MeSH descriptors today does not exist in the OLDMEDLINE files. This requires more inputting of keywords in the search.

Another thing to keep in mind is that the older records in MEDLINE do not have abstracts and that fewer descriptors were assigned to articles back then. This limits the number of access points available for searching. Descriptors for the concepts human, animal, male, female were not systematically added to each record so searching for them is unavailable.

The only Publication Type in OLDMEDLINE is "Journal Article" so it is not possible to search for Review articles, Guidelines, Editorials, Clinical Trials, etc. using that handy device. Searches may be limited to OLDMEDLINE by using the Limits Menu in PUBMED or by selecting the OLDMEDLINE database in Ovid link removed.

If you have any doubt about the results you receive from a MEDLINE search that goes back to the years before 1966, please contact one of the Reference link removed Librarians at 568-6102 or 568-8339 for the Isché Library or at 619-8507 at the Dental Library link removed.

-- Mary L. Marix link removed