All Carnegie Library of Pittsburgh locations will be closed on Wednesday, December 24, Thursday, December 25 and Thursday, January 1, 2015. In addition, the Library will close at 5 pm Wednesday, December 31, 2014.
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Library of Congress Classification System

The Carnegie Library of Pittsburgh uses the Library of Congress Classification System. The Library of Congress offers an overview of the classes. See our Library Subject Guide for more help with Subject Headings.