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Library of Congress classification: Reading and Understanding LC Call Numbers

Finding what you want: how to read LC call numbers to find materials in the Library.

LC Classification System

Want to learn where books or videos on a topic are on the shelf?
Take a look at this detailed 2 page list of topics and corresponding LC class letters.

How to read a call number step by step

As an example, with call number DS340 .R57 M34 1995, read it one line at a time.

  DS Read in alphabetical order: The first line can have from 1 to 3 letters. D is the Main Class for History and DS is the Subclass for History of Asia.
  340 Subtopic is read as a whole number from 1 to 9999. (340 is for Southern Asia, Indian Ocean Region.) If the letters on the first line of the call number are the same, the book with the smaller number on the second line is shelved to the left of the book with the larger number.
  .R57 This is the Cutter Number for the author's last name, or organization's name, or the first word in the book title. Read the initial letter in alphabetical order and any numbers that follow it as decimals.
  M34 In the event that a call number has two Cutters, you should read the second Cutter just as it appears, as a whole number (without a decimal).

In most cases this is the year of publication, or a Volume number or a Copy number.