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Call Numbers Demystified

Most items in the TCU Library are shelved by Library of Congress (LC) call number. Federal government documents are shelved by Superintendent of Documents (SuDocs) numbers and music and media materials are shelved by a unique number.



Reviewed 06/01/2012 by Ammie Harrison.


Library of Congress call numbers

Every item in the TCU Library has a unique call number. Most of the items in the library have a Library of Congress (LC) Classification number. A call number is simply an address for a book or other material in the library. No two items will have exactly the same call number. All LC call numbers begin with letters of the alphabet.

The first letter stands for a broad subject grouping.

J - Political science
L - Education
N - Fine arts

Each letter and number that follows the first letter narrows down the subject.
JC - Political theory
LA - History of education
NC - Graphics arts, drawing, design, illustration

In general, an LC call number will look something like this:

1st set   QA
2nd set  349
3rd set   .M613
4th set   W4

Complete LC call number:   QA349.M613 W4

LC Call Number Guide Image


If you have problems locating an item in the library, please ask for help at the circulation, periodicals or reference desks.

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Reviewed 11/30/2009 by Laura Steinbach.

Government Documents call numbersFDLP Logo

As a Federal Depository Library, the TCU Library receives many publications issued by agencies of the U.S. Government. These publications, which may include books, maps, posters, pamphlets and periodicals, contain information on careers, business opportunities, space exploration, health, nutrition, energy and many other subjects.

Federal Government publications in this collection are arranged by the Superintendent of Documents (SuDocs) classification number.

Publications are grouped together by issuing agency.*  To ensure that you find all of the material available on a particular subject, be sure to check the indexes recommended by the librarian.

The example below shows how the SuDocs classification number C 61.48:998 is constructed for the publication
U.S. Industry & Trade Outlook:

C 61.48:1998

Commerce Department (Issuing Agency) = C
International Trade Admin. (Subordinate bureau within the agency) = 61
Number designating the title = 48
Year of Publication = 998

*NOTE: Some materials are distributed to depository libraries in microfiche format. These materials are shelved in a separate area.

A TCU librarian will be happy to provide you with the prefixes for any government agency and any other information that can help you find the materials you want.

The SuDocs Classification System was designed specifically for United States government documents. It is a method of grouping government documents by the agency or department that created or issued the publication. This is different from the Library of Congress or Dewey Decimal systems that group items by subject.

Here are the prefixes from the SuDocs classification numbers for some other agencies that you may be interested in:

A          Agriculture Department
C 3       Census Bureau (Commerce)
D          Defense Department
E           Energy Department
ED         Education Department
GA        General Accounting Office
GS        General Services Administration
HE        Health & Human Services Dept.
I           Interior Department
I 19      U.S. Geologic Survey (Interior)
J           Justice Department
JU        Judiciary
L           Labor Department
LC         Library of Congress
S          State Department
SI         Smithsonian Institute
T 22     Internal Revenue (Treasury)
X, Y      Congress
Y 4       Congressional Committees



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Reviewed 11/30/2009 by Melissa Fairfield.

Music/Media Library sound recordings call numbers

The sound recordings collection is not accessible for browsing.  Please bring a call number to the music/media desk so that a staff member can retrieve your selection.

  • Call numbers consist of two components:
    1. letters identifying the format of the recording
    2. numbers giving the recording's location on the shelf e.g. YCD-249
  • There are two basic formats with four categories of letters.
    • CDs are identified as YCD
    • LPs (33 1/3 speed vinyl records) are identified as YL, SY or YLP.
      • YLs are generally older recordings, but contain some classic performances from the greatest artists of the early 20th century.

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Reviewed 11/30/2009 by Laura Ruede.

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