Materials are arranged according to the Library of Congress (LC) call numbers. The call number is the column of letters and numbers on the spine of the book.

QM Materials are arranged in alphabetical order by the top line of the call number,
366.2 in numerical order by the second line,
.D97 and in alphabetical then decimal numerical order starting with the third line.
1992 Sometimes call numbers include a year, or a copy or a volume number.

The Library of Congress Classification System uses 21 letters of the alphabet to represent the major branches or classes of knowledge.

Major branches or classes of knowledge
A General Works
B Philosophy, Psychology, Religion
C Auxiliary Sciences of History
D History: General and Old World
E-F History: Western Hemisphere
G

Geography, Anthropology,

Recreation

H Social Sciences
J Political Sciences
K Law
L Education
M 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