Call Number Locator

How to Read Call Numbers

Panitza Library uses the Library of Congress Classification System, which classifies books by subject. Each book is labeled with the so-called Call Number based on this classification system, which is used by the user to locate the book on the shelves.

A call number looks like this: BF448 .L45 2009

A Call Number usually starts with one or two letters (rarely 3).

The first letter represents one of the 21 general divisions of the system. In this case, B stands for Philosophy. The second letter is a subdivision of the general subject, in our case BF stands for Psychology. The numbers after the letters are yet a greater subdivision of the subject; in this case Call Numbers in the range BF309-499 stand for Consciousness. Cognition.

The second part of the Call Number gives information about the author, and the last is the year of publication. Some Call Numbers might have other information as well, such as Vol.1 (Volume 1), c.2 (Second Copy) and so on. (The Book with the abovementioned Call Number is How We Decide, by Jonah Lehrer)  

Once you locate the book in the Catalog, you have to write down its Call Number in order to actually find the book on the shelves. The books are organized alphabetically by their first letter, or letters (just like they will be organized in a dictionary). Single letters come before the combination of letters.


  • B comes before BA   
  • BA comes before BF   
  • BF comes before C

When you go to the place where the BF section is located, start reading the numerical part of the Call Number. The number is read in a basic numerical order. Some numbers even have decimals.


  • N3 comes before N43   
  • N43 comes before N548.4   
  • N548.4 comes before N1952.4   
  • N1952.4 comes before N8647

When you locate that number on the shelve, you start reading the third part – a combination of letter and number, with the letter always coming first: Letters are always read alphabetically, and the number is read as a decimal (e.g. .2, .24, .29, .35, .35895).

Circulation collection locations:  

  • Call numbers A – N: Basement   
  • Call numbers P: First floor   
  • Call numbers Q - Z: Second floor   
  • Large books collection: Ground floor   
  • Reference collection:Ground floor
  • Storage: Basement
  • Marks collection: Basement, Compact shelves

See also Video Tutorial

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