A call number is like an address--it tells you where in the library you can find an item.

Here is an example of a call number for a book from our library. Let's see what a call number is made up of:


TK--The first letter or letters represent the General Subject Area--in this case, 'TK' stands for Electrical Engineering; Electronics; Nuclear Engineering

5105.882--the numbers in the second line of the call number represent a more specific subject area--here, it stands for aspects of, or services on the internet, browsers.

.M39-- Author or title. For this book, it stands for Maze, Susan.

1997-- Year of publication.

This book is Authoritative Guide to Web Search Engines by Susan Maze.

Here's another one:

E--The General Subject Area is United States History

332--This more specific subject area represents biographies of Thomas Jefferson.

.R196--This stands for the Author's last name, in this case Randall.

1993--Year of publication.

The book is Thomas Jefferson: a life by Willard Sterne Randall.


Call numbers are read line by line.

1. Read the first line in alphabetical order:
A, B, BF, C, D, ...L, LB, LC, M, ML ...

2. Read the second line as a whole number:
1, 2, 3, 45, 100, 1000, 2000, 2340 ...

3. The third line is a combination of a letter and one or more numbers. Read the letter alphabetically. Read the number(s) as a decimal.
.C65 = .65 .C724 = .724

Example: .B before .C -or- .34 before .55 -or- .554 before .63

Some call numbers have more than one combination letter-number line.

Example: RC 607 .A26 S56 1989
RC stands for internal medicine
607 .A26 stands for AIDS
S56 represents the author's last name--Silverstein
1989--the year of publication.

The book is AIDS: deadly threat by Alvin Silverstein.

4. Read the date chronologically:
1776, 1848, 1929, 1964, 1998, 2003

Some call numbers don't have dates, especially if it represents the first edition of a work or if it was published before 1982 (that's when the Library of Congress began requiring that the date be added to the last line of all call numbers).