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Illinois Tech Library Guides

Research Methods Class

Find Books

Step 1: Search for a book in the library online catalog.

You can search for books by keyword, title, author, subject, and/or ISBN. 

Step 2: Use the Call Number to find the book on the proper bookshelf

You need to know three things:

  1. Call Number: to identify the book on the shelf
  2. Location: to be directed to the appropriate area in the library
  3. Available or not available

What is the Call Number?

  • Books are organized on the shelves using unique identification numbers known as Call Numbers. Most academic libraries use the Library of Congress system. 
  • They look like “QA13.M374 2007” or “306.2 C582.”
  • Different call numbers have their own subjects; for example, Q: Science, QD: Chemistry, TK: Electrical Engineering.
  • For a full list, click here.


Reading Library of Congress Call Numbers


  1. First line of the call number - Alphabetical. (Single letters preceed letters combined in alphabetical order)
  2. Second line - Numeric (whole numbers which may run into the thousands).
  3. Subsequent lines - Alphabetical, then Decimal Numeric.

Example of call numbers in order:

  1. Q181.A286 2008
  2. Q310.J65 2008
  3. QA13.M374 2007

Call numbers will look like this on the shelves:

Book 1:     Book 2:     Book 3:
Q                 Q                QA
181             310            13
A286           J65            M374
2008          2008          2007