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Answered By: Katy Webb
Last Updated: Aug 12, 2014     Views: 169

ECU Libraries use the Library of Congress (LC) classification system to assign call numbers to most materials. LC call numbers start with one or more letters (A-Z). The first letter represents the broad subject assigned to an item; subsequent letters and numbers identify it more precisely. For example, the call number QH 361 .E34 1989, for the book Blueprints: Solving the Mystery of Evolution , by Maitland Edey, can be broken down this way:

Q : Science
QH : Biology
QH 361 : History of Evolution
QH 361 .E34 : Individual item on this topic authored by person with surname beginning with "E"
QH 361 .E34 1989 : 1989 indicates the year the book was published.

How to read a call number:

  • Single letters are filed before double letters in alphabetical order: Q, QA, QB . . . R, RA, RB, etc.
  • First numbers are filed in numerical order. If there is a decimal point, treat the number after it as a decimal: QA 76 comes before QA 77. QA 76.55 comes before QA 76.6
  • Second letters are filed alphabetically: QA 76.55 .G63 comes before QA 76.55 .H21
  • Numbers coming after the second letter are decimals. QA 76.55 .G63 comes before QA 76.55 .G7
  • The call number may have a final part denoting the year or volume, like QA 76.55 .G63 1994 or QA 76.55 .G63 v.2

Here is a chart showing a broad breakdown of Library of Congress call numbers.

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