Southern Illinois University Edwardsville Logo
Apply to SIUE
Library and Information Services
Library and Information Services
Institutional Header

Understanding Call Numbers

How are the books in Lovejoy Library arranged?

  • Lovejoy Library, like most academic libraries, uses the Library of Congress Classification System (commonly referred to as LC) to group books by broad categories. A unique combination of letters and numbers identifies each separate book in the Library.
  • The LC System organizes materials according to twenty-one categories. The categories (labeled A - Z excluding I, O, W, X, and Y) are further divided by the addition of one or more letters and a set of numbers. Understanding that books arranged using the LC System are grouped by subject allows users to locate additional relevant resources on the subject in the same area.

How are separate books identified?

  • Each book in the Library has its own unique identity code called a Call Number that indicates where a book is shelved. A Call Number may be formatted differently on the spine of the book than it is in the online catalog.
On the spine of a book as:
In the Library's Online Catalog as:
LB2369 .G53 1999

Where are separate books located?

  • The Collections Directory will indicate where books, materials, and other resources are shelved or stored.
  • Some call numbers contain a Special Location Symbol. For example, a call number that is prefaced with REF indicates that the book is shelved in the Reference Collection rather than the general collection. Below is a list of some of the common Special Location Symbols and their respective locations:
    • ARCHIVE Archives - Basement
    • FOLIO Oversized Books - 2nd Floor
    • REF Reference - 1st Floor
    • RES Course Reserves - 1st Floor
    • SPECIAL Special Collections - 3rd Floor
  • Users wanting to access material in Special Collections must submit a request at the Circulation Desk. A staff member will then retrieve the item.
  • If a book is not on the shelf in its appropriate location, remember to: check the sorting shelves located near the area; consult the staff at the Circulation Desk to inquire whether the book is in the process of being re-shelved; or, if the book is lost, submit a request for the book at the Information Desk.

Reading a Call Number

MLA Handbook image
TITLE: MLA Handbook for Writers of Research Papers
AUTHOR: Gibaldi, Joseph
CALL NUMBER: LB2369 .G53 1999

  • Library of Congress call numbers usually contain four distinct lines:


  • The first line of an LC call number indicates the subject area and may contain either a single or double letter. The book with the single letter is shelved first (or to the left) on the shelf. For example, in the section for call numbers beginning with L, the correct sequence would be L, LA, LB, LC, etc.
  • The second line of an LC call number is always a whole number from 1 to 9999. If the letters on the first line of a call number are identical, the book with the smaller number on the second line is shelved first (or to the left) of the book with the larger number. For example, in the section for call numbers beginning with P, the correct sequence would be P45, P206, P2063, and P4508.
  • The third line of an LC call number usually represents the author's last name or the title of the work. This line always begins with a decimal point and is followed by a letter and number. Books are shelved alphabetically according to the letter to the right of the decimal point. For example, a book with .G on the third line of its call number would be shelved before (or to the left of) a book containing .H in the third line. If two books have an identical letter on the third line, then the book with the smaller decimal number is shelved before (or to the left of) the book with larger number. For example, .G53 is shelved before .G532 because .53 is a smaller decimal number than .532.
  • The fourth line of an LC call number always represents a year of publication or a volume number. An earlier edition of the same work is always shelved before (or to the left of) a later edition. Likewise, a lower volume number is shelved to the left of a higher volume number.

For additional assistance contact Lydia Jackson, Instruction Librarian ( or 618-650-2604) or the Information Desk (618-650-INFO).

facebookoff twitteroff vineoff linkedinoff flickeroff instagramoff googleplusoff tumblroff socialoff