Research Process: Call Numbers

Prince George's Community College uses the Library of Congress Classification System, an alphanumeric system, for classifying and locating books, videos, CD's, DVD's, and other sources. This system assigns each type of item a unique call number, which is its "address" and subject matter.

Call Numbers

Each call number contains both letters and numbers like an address to locate sources in the library. Books and other items can be found through accessing the online catalog.

 HV 6432 .C36 2001

Reading Call Numbers

Remember the Library of Congress Classification system arranges books and other items by subject. Fiction books are classified by a call number according to its subject. After the book is cataloged and processed, the call number is put on the spine of the book.

• Books are shelved from left to right by the call number on the spines. They are arranged alphabetically according to the letter(s) of the first letter of the call number such as A, B, C, D, DA, DB, etc.

• Books that start with the same letters are shelved numerically by the number on the second line.  

• Books with the same letters and numbers are arranged alphabetically by the letter and numerically by the third row. The number is read as a decimal.

• Books sometimes require a fourth line when the first three lines are identical. The fourth line is arranged alphabetically by letter and then numerically.

The last line of the call number may include dates, volumes, issues, and copy number. Editions of books with the same call number but have different dates are shelved in chronological order with the earliest date first.

What does a call number mean?

Remember that Library of Congress Classification arranges materials by subject. The first sections of the call number represent the subject of the book. The letter-and-decimal section of the call number often represents the author's last name. As you probably recall, the last section of a call number is often the date of publication.

For example:

Source: Call Number, a section of LINKS: Module 1 by Lansing Community College.

This video teaches the basics of the Library of Congress Classification system. (Video from the Valley Forge Christian College YouTube Channel)