TWU Libraries

Understanding Library of Congress (LC) Call Numbers

Our catalog uses the Library of Congress classification system, an alphanumeric system which groups books by subject categories, or classes.

What is a call number?

A call number is like an address; it tells you where the book is located on the shelf. Each book has its own unique call number, which is attached to the book's spine. A book's call number also appears in the catalog entry in the library's online catalog.

Reading Call Numbers

The Library of Congress arranges materials by subject. The first section of the call number represents the subject of the book. The second section often represents the author's name, and the last section is the date of publication.

In the following example of a call number for the book
How to ace calculus: the streetwise guide by Colin Adams QA303.3 .A33 1998
QA303.3 is the subject,
A33 represents the author's last name (Adams), and
1998 is the year of publication.

Shelving/Filing Rules of LC Call numbers

D
33.6
.A23
1999

DE
33
.J11
1986

L
899
.T2
2003

LB 65
.R45 2001

LM 898
.B55 1988

Q
23
.Z55 1923

QC
11
.H2
2001

QL
400.2
.H33 2002

R
990.1
.J66
1978

RA
45
.N4 2003

Single letters are filed before double letters:

The second part of a call number is made up of a number that may have one or more digits. This line is read numerically. A call number with a smaller number is shelved before one that has a larger number.

QA
3
.B777

is shelved before

QA
303
.A123

Some of these numbers may be divided by a decimal point : these are also read numerically (smaller numbers are shelved before larger numbers).

QA
3.98

is shelved before

QA
39

Remember there are several collections of materials located in different areas of the TWU Libraries. You will find the LOCATIONS on the spine of your book above the call numbers. Examples of locations in the TWU libraries include: Main , Reference, Parkland , Presby, Woman's, Texas Documents, etc.

LIBRARY OF CONGRESS CLASSIFICATION OUTLINE

Listed below are the letters and titles of the main classes of the Library of Congress Classification.

A -- GENERAL WORKS
B -- PHILOSOPHY. PSYCHOLOGY. RELIGION
C -- AUXILIARY SCIENCES OF HISTORY
D -- HISTORY (GENERAL) AND HISTORY OF EUROPE
E -- HISTORY: AMERICA
F -- HISTORY: AMERICA
G -- GEOGRAPHY. ANTHROPOLOGY. RECREATION
H -- SOCIAL SCIENCES
J -- POLITICAL SCIENCE
K -- LAW
L -- EDUCATION
M -- MUSIC AND BOOKS ON MUSIC
N -- FINE ARTS
P -- LANGUAGE AND LITERATURE
Q -- SCIENCE
R -- MEDICINE
S -- AGRICULTURE
T -- TECHNOLOGY
U -- MILITARY SCIENCE
V -- NAVAL SCIENCE
Z -- BIBLIOGRAPHY. LIBRARY SCIENCE. INFORMATION RESOURCES (GENERAL)