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HELP: Using Library Services: Library Call Numbers

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How to Read a Library of Congress Call Number

  1. The first line of a Library of Congress call number may begin with one, two, or three letters. Read these letters alphabetically. A call number that begins with A is shelved before one that begins with B, C, etc.; a call number that begins with QE is located before one that starts with QL.
     QE  
        

     
     comes
     before
     QL  
        

     
  2. The second line is a number that may have one or more digits. Read these as whole numbers. Therefore:
     HD
     98  

     
    comes
    before
     HD
     587  

     
    comes
    before
     HD
     1001

     
  3. The third line combines a letter and numbers. This is the tricky part of the call number! The letter is shelved alphabetically, and the numbers after the letter are decimal numbers.. Note the decimal point before the letter--it's like a reminder that the number is a decimal! Therefore:
     QE
     352
     .C444
     1999
    comes
    before
     QE
     352
     .C64
     1999
    comes
    before
     QE
     352
     .C7
     1999
    comes
    before
     QE
     352
     .C754
     1999

    This order makes sense if you read the numbers as decimals.

     0.444 
    comes
    before
     0.64  
    comes
    before
     0.7   
    comes
    before
     0.754  
  4. The final lines of Library of Congress call numbers may include:
    • Another combination of letter and numbers (the "S46" in the example below). Although there's no decimal point, keep reading the numbers as decimals (in this case, 0.46):
       HQ
       784
       .I58
       S46
       2005
    • Publication Date (the "2005" in the example)
    • Volume or issue numbers
    • Copy numbers
    • Other annotations (for example: "supplement")

 

(This description is derived from a tutorial created by Humbolt State University Library.)

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