What is a call number? How do I read a call number?

Books and other physical items in Memorial Library are organized by call number, a series of letters and numbers. Review the information below to read a call number.

Answer

What is a call number?

Most of our materials are organized on the shelf using Library of Congress call numbers, a mix of letters and numbers.

  • It's like an address.
  • It determines the book location (or other item) on the shelf.
  • It represents what an item is about based on a classification system.

You need to search MavScholar to find an item's call number.

How to do I read a call number?

The call number listed in MavScholar will look like: DA 36 .A77. On an actual item, the number will usually appear on a label like this:

DA
36
.A77

Start with the letters

Read one line or section at a time.

Books are arranged in alphabetical order, by the letters on the first line of the call number. For example, first come all the D call numbers, then all the DA call numbers, then DB, etc.

Line 2 or the first segment of numbers

Within the DA call numbers, books are arranged in number order. Read it as a whole number, so 4 comes before 36.

Line 3 or middle segment with a letter and numbers

Line 3 of the call number has a letter and a number. The letters are in alphabetical order.

Once you find the letter, read the number. But note these are decimals not whole numbers.

Example: .A77 is read as A .77. This is why A77 comes before A8 (A .77, A .8, A .85).

Final lines or segments

The call number may end with information like the year of publication, volume number, or edition.

Content on this page is adapted from the University of Arizona Libraries How to read call numbers, licensed under a Creative Commons Attribution 4.0 International License and MIT Libraries About Search Our Collections: Library of Congress Call Numbers, licensed under a Creative Commons Attribution-Non Commercial 4.0 International License.

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  • Last Updated Jan 26, 2026
  • Views 3
  • Answered By Memorial Library Team

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