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PAL Research Guide

How to Read Library of Congress Call Numbers

When you find a call number in the library catalog, you will notice that it is written differently from how it is presented on a book or score. In the catalog, it is written all on one line:

The first part, in the green box, tells you which library the book can be found. It could be Chicago Library, Schaumburg Library, Performing Arts Library, or somewhere else.

The second part, in the blue box, tells you which part of that library you can find it, this can include Stacks, Reserve, Reference, etc.

The third part, in the red box, tells you where you can locate it and is made of a few parts.

The first part, underlined in red, is the subject of the book. On the shelf, books are arranged alphabetically by subject. This can also be referred to as the classification.

Books are then sorted by topic, underlined in blue. The topic of a book is a category of the subject or classification. These topics are different for each classification.

Underlined in green is what librarians call a Cutter number, and are used to group multiple books together on the shelf. Often times they are grouped by author or in some cases the series the books are a part of.

Lastly, librarians include the year of publication as the last part of the call number. This is underlined in black.

Sometimes, a book will begin with "REF", in which case that book can be found in the reference section. A book could also end with more text or other information after the year of publication. This is more common with music scores, but can be used to show the volume number of a book, the opus number of a musical work, or other information.

In contrast, the call number when written on the spine is layed out so that it is easier to read each part of the call number. The same call number is displayed below with arrows pointing to each part of the call number. The colors of the arrows correspond with the parts of the call number underlined above.

When multiple books are on the shelf, they are ordered alphabetically and numerically according to each part of their call number. See the example below.

Visual guide showing what order numbers and letters are read in a LC call number.

(Image is taken from St. Cloud University's library page)

In the above image, you can see how books are arranged on the shelf according to their Library of Congress call numbers: they are arranged left to right, first sorted by their Classification, then by their Topic, then any Cutter Numbers used for their title or the author, and then lastly their Year of Publication.

Library of Congress Classification Letters

Call numbers group materials on similar subjects together to facilitate browsing. So, if you find one book that closely matches your topic, you will likely find others next to it on the shelf that fit with your research. This does not mean that ALL books on a topic will be in the same section, however. For example, books on "women in politics" might be located under women's studies, political science, history, sociology, and more - all of which are shelved in different areas of the library.

The beginning letters of an LC call number indicate what broad classification your book is in. To get a sense of where books on particular topics are located in the library, click on any of the links below and find the letter on the library map.

A - General Works

B - Philosophy, Psychology, Religion

C - Auxiliary Sciences of History

D - World History

E/F- History of the Americas

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


Z - Bibliography