How do I read Library of Congress call numbers?


Items at Sprague Library are arranged according to the Library of Congress Classification Scheme. This classification scheme arranges works by subject so the call number of an item gives an indication of the subject matter, in addition to telling where specifically the item can be found on the shelf. In the library, books beginning with A-Q can be found on the library's upper level, and books beginning with R-Z can be found on the lower level. If you are having trouble locating a book on the shelves, always feel free to ask for help at the reference desk or access services desk. Call numbers are located on (or near) the spine of the book and are made up of a combination of numbers and letters that are read left-to-right, top-to-bottom.

First letters: one, two, or three letters that are arranged alphabetically. So K comes before KF which comes before KFD

 Close up of three book call numbers, K3240.F88, KF 843.5.U58, and KFD 401.A6H65. The letters K, KF, and KFD are bolded in red respectively.

Second letters: are preceded by a decimal point and are arranged alphabetically. So .B comes before .L which comes before .M.

Close up of three book call numbers, HA211.B37, HA211.L5, and HA211.M33. The first letters after the decimal B, L, and M are bolded in red.

Second numbers: are treated as decimals. So .33 comes before .813 which comes before .9.

Close up of three book call numbers L 901.C33, L901C813 and L901.C9. The numbers 33, 813, and 9 are bolded in red.

There may be another letter-number combo. If there are, these numbers will be read as decimals as well.

Year: If there is a string of four digits at the end of the call number it usually signifies the year and should be read as a whole number.

Tips: Because books are organized into subjects that go from very broad to very specific, a book you are looking for will be surrounded by other books on the same topic that may be useful to you as well. You can also do this kind of browsing virtually in the library catalog. Click on a print book title and then look for the "Browse the Shelf" feature on the bottom of the page.

This guide was modified with permission from the University of Louisville Libraries.


  • Last Updated Mar 04, 2022
  • Views 21
  • Answered By Erika Dragonetti

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