A “known item” search is a search for an item or article when you have some or all of the bibliographic citation. For example, how would you search for the citation given below in the PsycINFO database or any other research literature database.
Whicher, E. V., Utku, F., Schirmer, G., Exam, S., Davis, P., & Abou-Saleh, M. T. (2012). Pilot project to evaluate the effectiveness and acceptability of single-session brief counseling for the prevention of substance misuse in pregnant adolescents. Addictive Disorders & Their Treatment, 11(1), 43-49. doi:10.1097/ADT.0b013e3182387029
Most research literature databases index nearly all of the major bibliographic components of a citation, e.g. author(s), words from the article title, words from the journal title and even words from the abstract of an article.
Guidelines for an efficient and effective search
Here is how the above search might look in the PsycINFO database.