How to read call numbers in an academic library

Libraries use classification systems to organize items on the shelves. A classification system, such as the Library of Congress Classification System (LC), uses letters and/or numbers (call numbers) to arrange items of the same topic together.

Anatomy of a Library of Congress Call Number

Book title: The Gospel according to Luke.
Author: Michael F. Patella.
Call number: BS 2595.53 P44 2005

The first two lines describe the subject of the book.

  • Bible. N.T. Luke -- Commentaries.

The third line often represents the author's last name.

  • P = Patella

The last line usually represents the date of publication.

  • 2005

Tips for Finding Books on the Shelf

Read call numbers line by line. Consider the call number "BS 2595.53 P44 2005 ".

Read the first line in alphabetical order: A, B, BF, BS, BX, C, D...

Read the second line as a number (sometimes with decimal extensions), eg.: 1, 2, 3, 100, 1000, 2000, 2595.53, 2595.54, 2596...
If number has a decimal extension, read the decimals one digit at a time, eg.: .53 reads as "five, three" and not "fifty-three."

P44 (sometimes written as .p44)
The third line is a combination of a letter and numbers. Read the letter alphabetically and read the number as a decimal extension, that is, one digit at a time, eg.: .P433, .P44, .P5... ("four, four" comes before "five").

The last line is usually a date. Read in chronological order: 1985, 1991, 1992, 2005, 2006...

Here is a shelf of books with the call number order explained.