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Understanding Call Numbers

An easy, simple guide to understanding and using call numbers

Learning Call Numbers

Call numbers are meant to be read just like words.  Treat them like a road map when trying to locate a book or other material on the shelves.  They are usually located on the spine of a book, or the front of the item.



Parts of the Call Number

PS3200 - the subject area where the book is located

  • PS is located alphabetically between PR and PT
  • 3200 is read as a whole number, and is located between 3199 and 3201

.P82 - additional information about the book, sometimes more than one line

  • .P is located alphabetically between .O and .Q
  • A dot or period is located at the beginning of this number set
  • 82 is read as a decimal number, and is located between .P819 and .P821

2008 - year of publication

Call Numbers in Progression on the Shelf

Call numbers are arranged in alphanumeric order on the shelves.  Therefore, this call number would appear in progression as:

PS3200     PS3200     PS3200
.M435       .P82         .T908
1998         2008        2003

Finding Books

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How to read our call numbers


Call Numbers Defined

Call Numbers are used to find, reshelve, and organize books and other materials on the shelves.  The FIU Libraries, and most academic libraries, use the Library of Congress Classification.


  • Arrangement is by subject area
  • Shelves can be searched easily and quickly once the call number for a subject is known
  • Subject areas use letters A through Z
  • Letters and numbers are used to provide a specific location on the shelves
  • Arranged in alphabetical and numerical order
  • Call number labels are usually located on the spine or the front cover of the materials


  • Shorter call numbers indicate general and broad works in a subject area.  Example:  a general work about chemistry would have this call number -- QD37 .V3 -- because the book's content is general and broad.
  • Longer call numbers indicate works that are more specific or specialized.  Example:  a book about physical chemistry would have this call number -- QD432.2 D36 1979 -- because the book's content is about a specific field of chemistry.
  • No two materials should have the same, exact call number in the library.

Types of Call Numbers

  • LC - "Library of Congress" call numbers -- used in academic libraries, arranged by subject area
  • Dewey Decimal call numbers -- used in public libraries, arranged by subject area
  • Government Documents call numbers -- arranged by the government agency that issued the document, not by subject area
  • Other types for specialized libraries, such as medicine and law, usually arranged by subject area

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