How Items are Organized @Mason


A call number, like an address, tells where the item is located in the library. The Mason Libraries uses the Library of Congress (LC) Call Number system to organize materials on the same topic together. Each item begins with capital letter(s) followed by numbers. Use the item’s location and call number to find the title on the shelf.

Consider a source with the title The west: Encounters & transformations located in the Johnson Center Stacks at Call Number CB245 .W455 2011. To read this call number froma  book on the shelf, you will look at the call number top to bottom, line by line. To read it from the record, you will read it from left to right. First, read the first letters in alphabetical order (ex. CB before CC). Second, read the next number as a whole number (ex. 245 before 246). Finally, read the letters after this alphabetically and read numbers after this as a decimal (ex. .W455 before .W555)

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Additional Questions and Help

If you tried to use this diagram and continue to have problems identifying what kind of sources you are working with, you could try asking a librarian or coming to a service desk for help.

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How to Read a Call Number is licensed under a Creative Commons Attribution 4.0 International License.