Understanding call numbers
- 1. Understanding call numbers: The Library of Congress classification system
- 2. Classification systems • To keep everything organized, libraries assign each book (or item) a call number which is unique. These call numbers are made according to the rules of a library classification system. • Many different library classification systems are used around the world. However, in the United States, almost all libraries use one of these two systems: • The Dewey Decimal Classification System • The Library of Congress Classification System
- 3. The Dewey Decimal System This system is currently used by almost all public and school libraries. All the knowledge of humanity is divided into 10 broad areas, using numbers in groups of 100. (000-099, 100-199, 200-299 etc.) • Each main area is then subdivided into smaller and smaller topic areas. This allows the library to organize the books so that everything on one topic is shelved together. • For example: 500s is the area for all Science and Math • within that, 590s are the area for Animals and Insects • within that, 598 is the area for books about birds • Within that, 598.47 is the section for penguins
- 4. The Library of Congress (LC) System This system is currently used by larger libraries, including most college and university libraries. All the knowledge of humanity is divided into 21 broad areas, using 21 letters of the alphabet. Each main area is then subdivided into smaller and smaller topic areas. For example: Q is the general area for Science • within that, QL is the area for Zoology • within that, QL 671-699 is the area for birds • within that, QL 696.S473 P46 is a call number for a book about penguins
- 5. Why is this important to know? Since books are classified by subject, you can often find several helpful books on the same shelf, or nearby. You can also browse by call number in the online catalog. So, which library has which call numbers? • Bird Library holds LC call numbers from A to P • Carnegie Library holds LC call numbers from Q to Z • The Architecture Reading Room has LC call numbers from A to Z, but most are in the NA section for Architecture
- 6. More about call numbers Since libraries organize the books by call number, each call number is like an address for that book. The call number is in two places: on the spine of the book (read top-to-bottom) and in the catalog listing for the book (read left-to-right)
- 7. What does the call number mean? How do you read it? Example The first two lines indicate the subject of this book LB 2395 = Methods of Study, in Higher Education This line often (but not always) represents the author’s last name. .C65 = Coman The year the book was published
- 8. More examples to show correct order