Research Help

The Mary Livermore Library uses the Library of Congress (LC) classification system, which organizes materials by subject. Library holdings are shelved by call number. Each call number is unique; call numbers serve as subject identifiers and as addresses for locations in the collections. Call numbers generally incorporate the subject classification, a code for the author, and year of publication. 

Library of Congress call numbers can be confusing since they frequently contain a letter or letters followed by whole numbers, and then a letter followed by decimal numbers. In reading a call number, begin at the top line and read from left to right; then proceed to the next line reading again from left to right as if reading a book.

Starting with the letter(s) at the top left of the call number books are ARRANGED ALPHABETICALLY:

Books having the same letter(s) on the top line are all shelved together by the number group that follows the letter(s). THESE NUMBERS ARE ARRANGED NUMERICALLY, NOT DECIMALLY:

(Sometimes the first 2 lines are combined but are read as above: QM 23; QM 123; QM845; and, QM 2345.)

When both the letter(s) and the number group that follows are the same, then books are shelved ALPHABETICALLY by the next letter:

 Books which are identical in first letter(s), in the number group that follows, and in the second letter, are then shelved by the next number group. THESE NUMBERS ARE ARRANGED DECIMALLY, NOT NUMERICALLY:

Oftentimes a call number will have a fourth line which contains a letter and a number or numbers. THE LETTER IN THIS LINE IS ARRANGED ALPHABETICALLY, WHILE THE NUMBER(S) IS/(ARE) ARRANGED DECIMALLY.

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