Libraries@Mason uses the Library of Congress Classification system to arrange books on the shelves so that books on the same topic are shelved together. Each book has a unique call number that begins with one, two, or three capital letters followed by numbers. Most call numbers appear on the spine of the book or video. A call number is like an address - it tells where the book is located in the library. Check it out! Read it! Read call number top-to-bottom, line by line LB First Line: read in alphabetical order. Example: LB before LC 2395 Second Line: read as a whole number. Example: 2395 before 2396 .C65 Third line: read the letter alphabetically. Read the number as a decimal. Example: .C6499 before .C65 1991 Last Line: can be publication date, volume or copy number and/or other annotation Find it! Guide signs posted on each book stack end indicate the "neighborhood" for the book's call number. Need help? Just ask! Librarians and reference desk staff can assist you.