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SOCY 122: Introduction to Academic Library Research

Course guide library research tutorial

Understanding Call Numbers

When you have located an item you want in the Library catalogue, it is important to record the call number, for the call number is like an address as to the exact location of the book on the Library's shelves.

call number

Call numbers in academic libraries are based on the Library of Congress (LC) Classification system. This A to Z classification scheme organizes books by main subject, so that books on similar topics will be shelved together. Once you have located the book you want on the Library’s shelves, you can browse the shelves in the same area for additional books on your topic. Clicking "show on floorplan" provides information about the library, floor, and general area where the item is shelved.

The following is a partial breakdown of the Library of Congress Subject classification for “H” Social Sciences:

library of congress classification

Sociology, HM, can be further broken down into subjects within the broader subject of sociology:

library of congress classification for sociology

Reading Call Numbers

The first letter of a call number represents one of the 21 major divisions of the Library of Congress Classification System. The subject "H" is General Social Sciences. The second letter "M" represents a subdivision of the social sciences, Sociology. All books classified in the HM's are primarily about Sociology.

call numbers

  • Books are shelved alphabetically by the first letter or letters
  • Books are then arranged numerically by the number following the letter(s)
  • Books are then shelved alphabetically by the next letter and decimally by the following number.