Please note:

Answered By: William Gee
Last Updated: Aug 03, 2023     Views: 515

In libraries, materials are often arranged using call numbers, labels on the side or front cover, of an item. This FAQ explains how to read the call numbers used by the ECU Libraries. Once you have the call number and can read it, referring to our How do I find it in the library FAQ might be helpful to you in locating it in the building. 

The ECU Libraries use a variety of classification systems to organize our vast collections and assign these call numbers. Joyner Library and the Music Library use the Library of Congress (LC) classification system to assign call numbers to most  of our materials, but items in the Teaching Resources Center use the Dewey Decimal System, Federal Documents use the Superintendent of Documents (SuDocs) Classification Scheme, and items in Special Collections (University Archives, Rare Books, and Manuscripts) use various classification methods. Items in the Laupus Health Sciences Library use the National Library of Medicine classification system, which is very similar to the Library of Congress classification system.

Library of Congress Call Numbers

The LC system places titles about a topic together, whether fiction or non-fiction, which means a novel and scholarly books discussing the novel are shelved together. To find the call number area for any topic of interest, consult the Library of Congress Classification Outline.

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, is 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.

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

Dewey Decimal System

The Dewey Decimal System uses ten general subject classes (see below). Narrower subjects are assigned more specific numbers (e. g. 940.3 for World War I). In Dewey, books are filed digit by digit, not by whole number, and after the decimal numbers may come letters from the author's name or title followed by another series of numbers.  For example, a book at 595.789 BRO would come after 595.0123 and before 595.9.

Ten Main Classes in Dewey Decimal Classification.

        000                  Generalities
        100                  Philosophy and Related Disciplines
        200                  Religion
        300                  Social Sciences
        400                  Language
        500                  Pure Sciences
        600                  Technology (Applied Sciences)
        700                  The Arts
        800                  Literature
        900                  General Geography and History

Joyner Library's Teaching Resources Center has prepared a Guide to Useful Dewey Decimal Numbers that can provide a quick introduction. If you would like assistance, please Ask a Librarian. If you are interested in learning much more, read the official Introduction to the Dewey Decimal Classification or consult the full Dewey Services website.



Superintendent of Documents (SuDocs) Classification Scheme

The SuDocs classification scheme is used for United States Federal Government documents. Items are arranged alphabetically based on the leading letter(s), which represent the issuing government agency (e. g. "A" stands for the Department of Agriculture). The number between the period and colon is a whole number (e. g. A 1.3: comes before A 1.15:). The following colon separates the SuDoc stem and its suffix; after the colon, the hierarchy of sorting is as follows: Date, Letters, Numbers, Words. For assistance, Ask a Librarian. For much more detail, consult the Federal Depository Library Program's Introduction to the Classification Guidelines.

SuDoc example

Special Collections (University Archives, Rare Books, and Manuscripts)

Joyner Library's Special Collections division uses a variety of specialized classification systems. Please Ask a Librarian for assistance accessing these collections. 

National Library of Medicine classification system

Health sciences and medical libraries often use the NLM classification system, which is an extension of the Library of Congress system that has more specialized sub-sections in the Q section and an extensive W section for medicine and related fields. For assistance, Ask a Librarian, consult the Outline of the NLM Classification or Detailed Poster, or visit the full NLM website.

Contact Us