Library of Congress Call Numbers

A General Works AE Encyclopedias  AY Yearbooks & Almanacs  B Philosophy/Psychology/Religion B-BD Philosophy  BF Psychology  BL-BX Religion  C: History: Related Fields CC Archaeology  CT Biography  D History (except N & S. American) E American History F Local History & Non US  History of North & South America G Geography/Anthropology/Recreation G-GF Geography  GN Anthropology  GV Recreation  H Social Sciences HA Statistics  HB-HJ Economics, Business, & Finance  HM-HX Sociology  J Political Science JK United States  JX International Law  K Law KFA Alabama Law  L Education M Music

N Fine Arts P Languages and Literature PA Classical Languages & Literature  PE English Language  PN Literary History PQ Romance Languages Literature  PR English Literature  PS American Literature  Q Science QA Mathematics & Computers  QB Astronomy  QC Physics  QD Chemistry  QE Geology  QH Natural History & General Biology  QK Botany  QL Zoology  QR Microbiology  R Medicine RM Pharmacology  RS Pharmacy  RT Nursing  S Agriculture T Technology TA Civil Engineering  TJ Mechanical Engineering  TK Electrical Engineering  TP Chemical Engineering  U Military Science V Naval Science Z Bibliographies and Library Science

Understanding Call Numbers

This tutorial was created to help library users uncover the mysteries of call number reading. Let's start with a sample call number:

QE534.2.B64

Call numbers can begin with one, two, or three letters.

• The first letter of a call number represents one of the 21 major divisions of the LC System. In the example, the subject "Q" is Science.
• The second letter "E" represents a subdivision of the sciences, Geology. All books in the QE's are primarily about Geology.
• Books in categories E, United States History, and F, Local U.S. History and American History, do not have a second letter (exception: in Canada, FC is used for Canadian history).
• Books about Law, K's, can have three letters, such as KFH, Law of Hawaii. Some areas of history (D) also have three-letter call numbers.
• Most other subject areas will have call numbers beginning with one or two letters.
• For most of the subject areas, the single letter represents books of a general nature for that subject area (i.e. Q - General Science or D - General World History).

Numbers after letters.

• The first set of numbers in a call number help to define a book's subject.
• "534.2" in the example teaches us more about the book's subject. The range QE 500-625 are books about "Dyamic and Structural Geology."
• Books with call numbers QE534.2 are specifically "Earthquakes, Seismology - General Works - 1970 to Present"
• One of the most frequently used number in call numbers is "1" which is often used for general periodicals in a given subject area.
• For example, Q1.S3 is the call number for the journal Science.
• Journals are also given call numbers based on the specific subject.
• For example, QE531.E32 is the call number for the journal Earthquake Spectra as QE531 is the call number for periodicals about "Earthquakes, Seismology"

Cutter Number

• The cutter number is a coded representation of the author or organization's name or the title of the work (also known as the "Main Entry" in library-lingo).
• Charles Ammi Cutter first developed cutter numbers using a two-number table.
• A three-number table was developed in 1969.
• In our above example, QE534.2.B64, the B64 is taken from the two-number table and represents the author's last name, Bruce A. Bolt.
• The book is Earthquakes.
• Some books have two Cutters, the first one is usually a further breakdown of the subject matter.
• For example, QA 76.76 H94 M88 is a book located in the Mathematics section of the Q's.
• QA 76 is about Computer Science.
• The ".76" indicates Special Topics in Automation.
• "H94" tells us that this is a book about HTML.
• "M88" represents the last name of the first author listed's last name, Musciano.
• The book is HTML: The Definitive Guide