Getting Started: Information Research Tips

Introductory help in learning how to identify, locate, evaluate, and use information effectively and ethically for research assignments.

How to Read a Call Number

Library of Congress call numbers are arranged alphabetically and numerically. Read call numbers from left to right and from top to bottom.

Letters in the first line of the call number are alphabetical:

H
45
.E37
1984
HA
155
.A5
1944
HB
21
.A33
1982
HC
13
.S47
1990

Numbers in the second line of the call number are in numerical order:

B
53
.D476
1990
B
785
.L44
M67
1991
B
1201
.B44
W64
1997
B
1246
.R66
1986

Letters in the third line are alphabetical:

KF
240
.B265
1981
KF
240
.C538
1989
KF
240
.S795
1995
KF
240
.T38
1989

Numbers in the third line of the call number are in decimal order. It is important to remember that there is an “invisible” decimal point between the letter and the number:

L
901
.C33
L
901
.C34
1971
L
901
.C343
1976
L
901
.C37
1996

There may be a fourth line of letters and numbers. These will also be in alphabetical and decimal number order.

The last line of a call number may be a year. This indicates the publication date.