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How to Read Call Numbers

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Library of Congress call numbers should be read one line at a time as follows:

Example of a complete call number:  

DA Line 1
36 Line 2
A77 Line 3


1. First, look at Line 1:

Books are arranged in alphabetical order , by the letters on the first line of the call number.

Example: first come all the D call numbers, then all the DA call numbers, then DB , etc.Books in order by Line 1

2. Next, look at Line 2:

Within the DA call numbers, books are arranged in number order .

The numbers are arranged in numerical order, from low to high.


Books in order by Lines 1 and 2


3. Then look at Line 3:

Line 3 of the call number has a letter and a number. The letters are in alphabetical order.

Then read the numbers -but BEWARE !

The numbers are not WHOLE numbers, they are DECIMAL numbers!


Example: A55 is read as A .55 - this is why A55 comes before A6 ( A .55, A .6, A .65, etc. )

Books in order by Lines 1, 2 and 3

Last modified: December 15, 2015