Q. How do I use a book's call number to find it at the library?

Montgomery College Library uses the Library of Congress classification system, which groups together books on similar subjects by their call numbers. A call number is like an address: it tells us where the book is located in the library. The call number is printed on a sticker on (or near) the spine of each book in the library.

To find the call number for a book, you need to first locate the book in RaptorSearch. Once you've found the item you want, note down the "Available at" information that displays with the listing on the results page. (You can also use the email or QR code features to send yourself the details about the item.) For example:

"Available at Rockville RV Circulating Collection (PS3562.E353 T645 2008)"

The books at the library are organized by call number in alphabetical and numerical order. The signs on the end of each shelf will tell which which range of call numbers can be found on that shelf.

To find the item in the example above, you need to break the call number up into its separate components:

• Start by finding the shelves that contain call numbers starting with PS.
• Within the PS books, look for the number following the letters: 3562.
  • This first number in a call number is treated as a whole number, so a call number starting with PS44 would come before a call number starting with PS3562, because 44 is smaller than 3562.
• Now all the PS3562 books will be organized alphabetically by the next letter in the call number, which in our example is .E.
• Now all the PS3562.E books will be organized numerically by the digits that follow, in our example, .353.
  • Unlike the first number in a call number, this number should be treated as a decimal, so compare this portion of a call number one digit at a time. For example, a call number starting with PS3562.E4 would come after PS3562.E353 because, looking at the first digits of this section only, 4 is bigger than 3. 
• If there are multiple PS3562.E353 books, they will be organized alphabetically by the next letter, T. 
• If there are multiple PS3562.E353 T books, they will be organized numerically by the digits that follow, 645.
  • Treat this number as a decimal, so look at it one digit at a time. PS3562.E353 T73 will come after PS3562.E353 T645 because, looking at the first digits of this section only, 7 is larger than 6.
• Finally, if there are multiple PS3562.E353 T645 books, they will be organized in chronological order by year, 2008.

If you cannot find a particular item, please go to the service desk and a library employee will be happy to help you.