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The Library of Congress Classification System

Most academic and research libraries classify, catalog, and shelve books according to the Library of Congress (LC) classification system.

Library of Congress Call Letters/Numbers

What do the call numbers mean?

    -Call numbers communicate valuable information about the book like...
        - The location of the book, or where the book is shelved and how to find it
        -The letters at the beginning of the call number indicate the subject of the book
        -Who the author of the book is
        -May also include information like the publication date, volume number, copy number

 

Note the Library of Congress Call numbers (a combination of letters and numbers) in the screenshot below - BF is the Psychology designation. Note, too that books on the same subject will be housed in the same area, which allows you to browse the shelves further for additional materials.

 

While the call numbers are noted in a linear fashion in the catalog record, the call letters on the book spine will look a little different with a vertical arrangement.

 

 

In the example shown QA is the classification area for Mathematics

A typical shelf will look as shown below - this image will help you "read" a shelf to find your particular book. You will also be able to find similar books on your topics - the value of browsing!

TIPS and HINTS 

  • There may be additional information before a call number, usually showing that an item is in a special location/collection - for instance REFERENCE BF 1000.T23 2017. In this example, the item is probably an encyclopedia of psychology and thus will be housed in the Reference collection in the library, available for in-house use and not for check-out.

  • The entire call number is important, write it ALL down, then check the entire number against the spine of the book to check that it matches.

      For example: 

LB 2095 .C63 1991        LB 2095 is read numerically.

                                      .C63 is read decimally. In call numbers with decimal points, note:

                                                 N42 comes before .N422

                                                                                                         .N422 comes BEFORE .N51

                                                                                            –Even though “422” is bigger than “51,” .422 is SMALLER than .51

  • ​The "Letters before Numbers" rule:  ​LB                    LB                    LB
                                                              2095                 2095                2095
    ​                                                          .H277               .H277              .42
    ​The H in the first two call numbers comes BEFORE the .42 in the third call number

  • ​The "Nothing before Something" rule:   LB               LB
                                                                        2095            2095
    ​                                                                    .H277          .H277
                                                                                                           2015
    ​Here, the second call number has additional information - the year of publication - so it would come AFTER the first call number. Remember that a call number without a year comes before a call number with a year.

  • Double Check! Does it look like you are in the right place? Are the surrounding books on the same subject? Occasionally books get misshelved.

  • Take your time, and ask a librarian at the reference desk to help you if you get stuck.