The Sudoc (Superintendent of Documents) Number system was created by the Government Printing Office, which oversees distribution of government publications to depository libraries, including the Barton College Library. Publications are grouped together by issuing agency rather than by subject. The first letter in the call number is usually the first letter of the agency which issued the publication.

Below is a list of the most commonly used prefixes:

A	Agriculture Department
C	Commerce Department
D	Defense Department
E	Energy Department
ED	Education Department
EPA	Environmental Protection Agency
GA	General Accounting Office
HE	Health and Human Services Department
HH	Housing and Urban Development
I	Interior Department
J	Justice Department
Ju	Judiciary
L	Labor Department
LC	Library of Congress
NAS	National Aeronautics and Space Administration
S	State Department
SI	Smithsonian Institution
T	Treasury Department
TD	Transportation Department
Y	Congress