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Information Storage and Retrieval

Notes When searching for chamber music for specific combinations of instruments, it often helps to search
the print volumes of LCSH to find the proper order in which to enter the instruments.

Singular and Plural

Often LCSH uses the singular of words to denote the treatment of the word as a subject and the
plural of the same word to denote individual examples of that subject. So searching under the
term Opera you will find books and other materials dealing with the subject of opera. Under the
term Operas, you will find individual operas (full scores, vocal scores, recordings videos).

Searching in the Online Catalogue

When using the Johns Hopkins online catalogue, you may do an alphabetical search for the LC
Subject Heading. When you find a useful item, follow the links for narrower or related subjects that
seem helpful. If you are not sure of the official subject heading, check the volumes of LCSH located
on the Index Table in the Reference area, or you may perform a Subject Keyword Search in the
online catalogue to find valid headings. Again, when you find a useful item, follow the links for
narrower or related subjects that seem helpful.

13.4 Medical Subject Headings (MeSH)

Medical Subject Headings (MeSH) is a comprehensive controlled vocabulary for the purpose of
indexing journal articles and books in the life sciences; it can also serve as a thesaurus that facilitates
searching. Created and updated by the United States National Library of Medicine (NLM), it is used
by the MEDLINE/PubMed article database and by NLM’s catalogue of book holdings.

MeSH can be browsed and downloaded free of charge on the Internet through PubMed.
The yearly printed version was discontinued in 2007 and MeSH is now available online
only.

Originally in English, MeSH has been translated into numerous other languages and allows retrieval
of documents from different languages.
From 6-15 subject headings are assigned for each article, with up to 3 assigned for major emphasis
of the article. Articles are indexed to the most specific term available to allow for very precise subject
searching. Subheadings, terms which cover general, frequently discussed aspects of a subject such
as adverse effects or therapy, are combined with MeSH terms to indicate the specific focus.
A particularly powerful feature designed into Medline allows users to “explode” a category of
terms in a hierarchy from general to specific to retrieve all of the articles on the general term and all
of the specific terms listed underneath. “Explode” is distinct from the concept of truncation in that
the terms do not have to begin with the same string of characters to be retrieved. “Exploding” a
term allows the information requestor to search a term and all levels of its narrower terms.

Structure of MeSH

The 2009 version of MeSH contains a total of 25,186 subject headings, also known as descriptors. Most
of these are accompanied by a short description or definition, links to related descriptors, and a list of
synonyms or very similar terms (known as entry terms). Because of these synonym lists, MeSH can
also be viewed as a thesaurus.

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