Books are arranged according to the Library of Congress Classification System.   Each call number starts with one or two letters. These letters represent the subject areas. Here is a list of what the letters mean:

A	General Works
B-BJ	Philosophy
BL-BX	Religion
C	Auxilary Sciences
D	World History
E-F	American History
G	Geography, Anthropology, and Folklore.
H	Social Sciences
HA	Statistics
HB-HJ	Economics
HM-HX	Sociology
J	Political Sciences
K	Law
L	Education
M	Music
N	Art
P	Language and Literature
Q	General Science
QA	Mathematics
QB	Astronomy
QC	Physics
QD	Chemistry
QE	Geology
QH	General Biology. Natural History.
QK	Botany
QL	Zoology
QM	Human Anatomy
QP	Physiology
QR	Bacteriology. Microbiology
R	Medicine
S	Agriculture
T	Technology
U	Military Science
V	Naval Science
Z	Bibliography and Library Science