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How to find a book on a shelf

Learn how to read a Library of Congress (LC) call number (classification) to find the item on the shelf.

Find a book using its call number

  1. In the Library of Congress (LC) classification, the call number starts with a letter (or two), followed by numbers. The letter indicates the subject
  2. Read call numbers line by line (see example below):
  3. callnumbers
  4. Books are shelved left to right

The call number is also on the book's spine or front cover:


Shelf signs in most libraries show the first part of the call number and the subject areas:


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Library of Congress subject areas

A General Works
B Philosophy, Psychology, Religion
C Auxiliary Sciences of History
D World History and History of Europe, Asia, Africa, Australia, New Zealand, etc.
E History of the Americas
F History of the Americas
G Geography, Anthropology, Recreation
H Social Sciences
J Political Science
K Law
L Education
M Music, Books on Music
N Fine Arts
P Language and Literature
Q Science
R Medicine
S Agriculture
T Technology
U Military Science
V Naval Science
Z Bibliography, Library Science, Information Resources (general)

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National Library of Medicine (NLM) subject areas

Preclinical Sciences

QS Human Anatomy
QT Physiology
QU Biochemistry. Cell Biology and Genetics
QV Pharmacology
QW Microbiology and Immunology
QX Parasitology
QY Clinical Laboratory Pathology
QZ Pathology

Medicine and Related Subjects

W General Medicine. Health Professions
WA Public Health
WB Practice of Medicine
WC Communicable Diseases
WD Disorders of Systemic, Metabolic or Environmental Origin, etc.
WE Musculoskeletal System
WF Respiratory System
WG Cardiovascular System
WH Hemic and Lymphatic Systems
WI Digestive System
WJ Urogenital System
WK Endocrine System
WL Nervous System
WM Psychiatry
WN Radiology. Diagnostic Imaging
WO Surgery
WP Gynecology
WQ Obstetrics
WR Dermatology
WS Pediatrics
WT Geriatrics. Chronic Disease
WU Dentistry. Oral Surgery
WV Otolaryngology
WW Ophthalmology
WX Hospitals and Other Health Facilities
WY Nursing
WZ History of Medicine. Medical Miscellany
19th Century Schedule

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Dewey Decimal System subject areas

000 Computer Science, Information, & General Works
100 Philosophy & Psychology
200 Religion
300 Social Sciences
400 Language
500 Science
600 Technology
700 Arts & Recreation
800 Literature
900 History & Geography


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