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University Library, University of Illinois at Urbana-Champaign

Information Literacy Tutorial: Finding Books

Learn how to find, evaluate, and manage sources with this guide.

Call Numbers

Call Numbers are the letters and numbers assigned to a book to give it a unique location in the library.

Guide Based On:

This guide is based on the Information Literacy Tutorial from the University of Wisconsin-Milwaukee.

Information Literacy Tutorial by Board of Regents of the University of Wisconsin System is licensed under a Creative Commons Attribution-NonCommercial 3.0 Unported License. Based on a work at

Creative Commons License

Finding Books with Library of Congress call numbers

Library of Congress

The Library of Congress classification system groups together books on similar subjects by call numbers beginning with letters which represent different subjects. Library of Congress call numbers are used in the Undergraduate Library and several subject libraries.

A list of the main classes of the Library of Congress Classification can be found at

Finding a Book on the Shelf:

1. Go in alphabetical order. For example, L comes before LA on the shelves. Also note that the more specific the number, the more specific the subject.


Example of LOC


                                   Least Specific                                                                          Most Specific


2. Numbers follow the letters. Search numerically. For instance, 774.5 comes before 774.59.

3. Sometimes the edition (the year of publication of the book) is included in the call number. It will be at the end.

  Example of LOC



To find a book's call number, search for the book in the catalog. On a book's information page the call number can be found under the "Holdings" tab, as highlighted below.


For more information on how to read LOC call numbers, see our guide on how to read a Library of Congress call number.

Finding Books with Dewey Decimal call numbers

The Dewey Decimal System

The Dewey Decimal is divided into ten subjects which are numbered between 000 and 999. Each number focuses on a specific subject. For example, the number 500 takes you to books on the natural sciences and mathematics. The more decimal places a call number has, the more specific the subject is. The Dewey Decimal system is used by the Main Library and several subject libraries.

 Example of Dewey Decimal


                                              Least Specific                                                         Most Specific

Finding Books on the Shelf

1. Search numerically for the first number. (Ex: 973 comes before 974)

2. Search numerically for the first number after the decimal point, and so on.

3. Sometimes Dewey Decimal includes letters in the call number (Ex: 973 C375). For these search alphabetically.

4. Remeber that "nothing" comes before "something." (Ex: 973 C375 comes before 973 C375a)

Example of Dewey Decimal


To see the subjects each Dewey Decimal number represents, see our guide to call numbers.

 Photos courtesy of Reference, Research, and Scholarly Services at the University of Illinois Urbana-Champaign. 4 Dec. 2014. Based on examples of call numbers from the "Dewey Decimal in the UIUC Bookstacks"