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What is a Call Number? 

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The call number represents what the book is about and determines where the book will be located on the library's shelves. Materials in the ASU Libraries are classified using the Library of Congress Classification (LCC).

This system divides all knowledge into twenty-one basic classes, which are identified by letters of the alphabet. Specific topics are further categorized with a combination of letters and numbers. The call number given in the Primo Online Public Access Catalog  book detail screen will match the spine label of the physical book. You may text the call number from the Primo Online Public Access Catalog to your smartphone (or take a picture) to make it easier to locate the appropriate book from the shelves.

For further information see Library of Congress Classification Outline at or visit