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Quick Guides

Understanding the Call Numbers

Understanding the Call Numbers:

Your Guide to Shelf Location in the Library


How are the Books & Journals Arranged on the Shelves in the Library?

Books, journals and other items are arranged by call number A-Z, using the Library of Congress Classification System.  It is as an alphanumeric system for shelf arrangement by subject.  The call number is a unique identifier that will help you to locate catalogued items in the library.

Reading a Library of Congress Call Number:

QA377.A83 2000






Read letters in alphabetical order

e.g. Q, QA, QB, QC...QH...etc.

Read as a whole number

Read numbers as a decimal

Read letters in alphabetical order

e.g. A83 comes before A9

Year of publication

in chronological order


Some call numbers are also followed by:

  • Volume number
  • Copy number (if more than one copy)


For the call number above, Q identifies the category for Science, and QA identifies the subclass of Mathematics.  The letter in the last portion of the call number, .A83, identifies the author, Asmar, followed by a decimal.  For journals or edited works the letter identifies the title rather than the author.  There may be two series of these numbers, followed by publication year, volume, copy.

Library of Congress Classification System: A-Z

A General Works M Music & Book on Music   Q Science
B Philosophy, Psychology, Religion N Fine Arts QA Mathematics
C Auxilliary Sciences of History P Language and Literature QB Astronomy
D History (General) & History of Europe Q Science QC Physics
E History: America R Medicine QD Chemistry
F History: America S Agriculture QE Geology
G Geography, Anthropology, Recreation T Technology QH Biology
H Social Sciences U Military Science QK Botany
J Political Sciences V Naval Science QL Zoology
K Law Z Bibliography, Library Science QM Human Anatomy
L Education Information Resources (General) QP Physiology
QR Microbiology