Understanding Call Numbers
This tutorial is intended to give you an overview of different Call Numbering systems and how they work. By the end of this tutorial, you will understand how items are classified within each system, what the call numbers mean and how to find an item based on it's call number.
Call Numbers - An Introduction
Materials in libraries have to be organized in some way so that things can be found once they have been placed on a shelf.Each item is assigned a unique code, called a call number, to help with organization.
- Call numbers are usually made up of numbers and letters and sometimes include punctuation marks like colons or dots
- Call numbers determine each item's exact location within a library
- Call numbers are assigned to items so that they bring together materials which are alike in some way, usually by subject
This tutorial will give a brief breakdown and explanation of several call number systems with tips on how to read the various numbers properly. A basic understanding of call numbers is necessary in order to find materials, and ultimately the information you need, in the library.
The most frequently use classification systems are :
- Dewey Decimal Classification System (Dewey) - Used by most public and school libraries.
Dewey call numbers begin with a three digit number.
In the online catalog, typical Dewey call numbers look like:- 813 AL355L 1987
On book spines, or labels on other materials, Dewey call numbers are arranged vertically and would typically look like:- 813
AL355L
1987
- Library of Congress Classification System (LC) - Used by most academic libraries and in other larger libraries.
LC call numbers begin with letters.
In the online catalog, typical LC call numbers look like:- PS 1017 L5 1983
On book spines, or labels on other materials, LC call numbers are arranged vertically and would typically look like:- PS
1017
L5
1983
- Superintendent of Documents (SuDocs) - Used by libraries with extensive collections of materials published by the United States Government
SuDocs call numbers begin with letters and always include a colon.
SuDocs call numbers typically look like:- HE 20.3002:R 24/5
LSU Libraries use all of the above systems, as well as some other classification systems which are specially suited to certain special collections.
Dewey Decimal Call Numbers
The Dewey Decimal Classification System is subject based, classifying and arranging items by the subject matter involved. LSU Libraries uses Dewey call numbers for materials in the Educational Resources Center, for theses and dissertations, and for older items which are used infrequently and are kept in compact storage.- Dewey call numbers begin with a three digit number
- The Dewey system is broken into 10 primary classes, or general subject areas, represented by the first digit of that number
- 000 - Generalities
- 100 - Philosophy & Psychology
- 200 - Religion
- 300 - Social sciences
- 400 - Language
- 500 - Natural sciences & Mathematics
- 600 - Technology
- 700 - The arts
- 800 - Literature & Rhetoric
- 900 - Geography & History
- The Dewey system further breaks these subjects into subclasses by the addition of the next two digits, and then often even adding a decimal point and more numerical digits. For example:
- 500 Dewey call numbers deal with Natural Sciences & Mathematics
- 590 Dewey call numbers deal with Zoological Sciences
- 599 Dewey call numbers deal with Animals
- 599.884 Dewey call numbers deal with Gorilla Behavior
- For a list of the major classes and subclasses of the Dewey Decimal classification system, click HERE.
- The second part of a Dewey call number is based on the Author's last name.
- Some libraries use only the author's name, or the first letters of the author's name.
For example, the call number for Gorillas in the Mist, by Dian Fossey would be:
599.884 FOS - Some libraries use the first letter, or letters of the author's name followed by numbers representing the author and the particular item.
In this case, the call number for Gorillas in the Mist is:
599.884 F752g
- Some libraries use only the author's name, or the first letters of the author's name.
- Frequently a Dewey call number will include a third part which represents the year that the item, or particular issue of an item, is published.
Again, the call number for Gorillas in the Mist:
599.884 F752g 1983
Library of Congress Call Numbers
The LC Classification System is also subject based, classifying and arranging items by the subject matter involved. LSU Libraries uses LC call numbers for most of it's books.- The LC system is broken into 21 primary classes, or general subject areas, represented by letters.
- By breaking items into 21 subject areas rather than the 10 of Dewey, the LC classification system allows libraries to classify and arrange larger collections.
- A - General Works
- B - Philosophy. Psychology. Religion
- C - Auxiliary sciences of history
- D - History
- E,F - History in Americas
- G - Geography
- H - Social Sciences
- J - General legislative and executive papers
- K - Law
- L - Education
- M - Music and 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
- The LC system further breaks these subjects into subclasses by the addition of one or two letters followed by numbers up to four digits plus several decimal places in length. For example:
- LC call numbers beginning with Q Science
- LC call numbers beginning with QL deal with Zoology
- LC call numbers beginning with QL 700 deal with mammals
- LC call numbers beginning with QL737 deal with Gorilla Behavior
The LC call number for Gorillas in the mist , by Dian Fossey is:
QL737 P96 F67 1983
- For a list of the major classes and subclasses of the LC classification system, click HERE.
- The second part of an LC call number includes a code representing the author and the particular item. This part of the call number begins with a letter followed by numbers, and them sometimes another letter followed by numbers.
For example, Gorillas in the Mist:
QL737 P96 F67 1983 - Frequently an LC call number will include a final part which represents the year that the item, or particular issue of an item, was published.
Again, Gorillas in the Mist:
QL737 P96 F67 1983
Here is a comparison of another work classified using both Dewey and LC systems. The work, Little Women, by Louisa May Alcott, would be classified as follows:
- in DC, as 813 AL355L 1987 and
- in LC, as PS 1017 L5 1983
| Dewey Decimal | Library of Congress | ||
| Classification Number |
813 |
Classification Number |
PS 1017 |
| Author and Book Number | AL355L | Author and Book Number | L5 |
| Year of publication (for this issue) | 1987 | Year of publication (for this issue) | 1987 |
Superintendent of Documents Classification System
SuDocs call numbers are issued by the United States Government Printing Office, for items published by the U. S. Government. The SuDocs Classification System is not a subject based system, rather, items are arranged by the department or the agency issuing the publication, such as the FBI or the Department of Health. As a Regional Depository for Government Documents, LSU Libraries uses the SuDocs Classification System for all government documents.For more information on Government Documents, see the Government Documents Tutorial
- SuDocs call numbers begin with letters which stand for the issuing government agency
- For a list of SuDoc department classification system, click HERE.
- After the department, other codes are added which represent agencies, the specific item, and date.
| Issuing Department | C | Commerce Department |
| Subagency | 3 | Bureau of the Census |
| Series | 134/2 : | Statistical Abstract Supplement |
| Title and date | C 83/2/994 | County and City Data Book, 1994 |
Note the COLON in the center of the call number. No other call number has a colon, so this is a quick and easy way to tell if the number is a SuDocs number.
Distinguishing features
Once you have a call number for an item you need, you will need to know what type of call number is in order to actually find that item.Characteristics to help easily identify, the system used:
- Dewey Decimal - begins with series of 3 numbers
Examples:- 302 H789I 1993
- 781.62 D184I
- 917.3 D141G
- Library of Congress - begins with one or two letters, followed by numbers
Examples:- E 174 U58
- LB 1062 B37
- Z 1037 A2 C67 2004
- Superintendent of Documents - begins with one or two letters, includes a colon (:)
Examples:- PM 1.9:1998
- GA 1.13:GGD
- Y 4.F 76/2:C 16/2/1993
How to Read the Call Numbers
Once you have a call number, and you know which kind of call number you are dealing with, what do you do with it?You use that call number to figure out where the item is and to actually find it on the shelf. To do that, it is necessary to read those call numbers in correct order.
Let's put the following Dewey Decimal call numbers in order:
| 823 D653e |
798.24 M1265a |
823 B189e |
821 L196 |
798.2 H985t |
823 D553d |
824 G987 |
Begin by comparing the entire number on the first line and put them in order from smallest to largest. So...
The "700" call numbers come before the "800" call numbers.
Then 798.2 is before 798.24, 821 is before the 823s and 824 is last.
| 798.2 H985t |
798.24 M1265a |
821 L196 |
823 D653e |
823 B189e |
823 D553d |
824 G987 |
The second line of the call number is considered a decimal so is compared letter by letter, digit by digit. So...
Of those 823 call numbers, the B comes before the Ds.
| 798.2 H985t |
798.24 M1265a |
821 L196 |
823 B189e |
823 D653e |
823 D553d |
824 G987 |
Of the remaining two call numbers, first line 823, second line beginning with D, compare the next digit. 5 comes before 6.
| 798.2 H985t |
798.24 M1265a |
821 L196 |
823 B189e |
823 D553d |
823 D653e |
824 G987 |
Let's put the following Library of Congress call numbers in order:
| PS 2552 O874 A6 2001 |
PK 2198 G4 A233 1999 |
M 1613.3 B94 L6 1990Z |
PN 1994 M78 1996 |
PS 3568 A486 W56 2001 |
PS 3 A47 1967 |
The first step is the easiest. Putting he first letters in correct order you get this:
| M 1613 .3 B94 L6 1990Z |
PK 2198 G4 A233 1999 |
PN 1994 M78 1996 |
PS 2552 O874 A6 2001 |
PS 3568 A486 W56 2001 |
PS 3 A47 1967 |
The next step is a little more tricky. The first set of numbers you come to are treated as a WHOLE number, and shelved in order from smallest to largest. So... 3 is before 2552 which is before 3568, which means PS 3 is before PS 2552 which is before PS 3568.
| M 1613 .3 B94 L6 1990Z |
PK 2198 G4 A233 1999 |
PN 1994 M78 1996 |
PS 3 A47 1967 |
PS 2552 O874 A6 2001 |
PS 3568 A486 W56 2001 |
Remember, the first leter(s) and the first set of numbers represent the subject of the item. The previous example deals with correctly ordering the subject portions of the call number, and if you can get to that area of the shelves, you will at least be in the right area to find materials in your subject area.
If you are looking for a specific item it is important to understand the correct order for all parts of the call number. After the first set of letter(s) and the first set of numbers, the call number is read differently. Rather than whole numbers, the rest of the call number is treated as a decimal, and each digit is read individually.
If you had the following call numbers:
| C 3 R3 |
C 3 R279 |
C 3 R2 |
C 3 R21 |
C 3 R1 |
C 3 R275 |
C 3 R38 |
It might help to think of them as:
|
Or even:
|
The first set of letters are all the same (C)
The first set of numbers are all the same (3)
The second set of letters are the same (R)...
| Second set of numbers - First digit. Move the "1" to top, group the "2"s then the "3"s: |
Second set of numbers - Second digit. Within the "2"s, the "0" is first, then the "1" then the "7"s. Within the "3", the "0" is first, then the "8". |
|
|
|
Finally, within the ".27_" set, the third digit, "5" then the "9".
|
Or...
|
Or finally...
| C 3 R1 |
C 3 R2 |
C 3 R21 |
C 3 R275 |
C 3 R279 |
C 3 R3 |
C 3 R38 |
This is the end of the Understanding Call Numbers Tutorial.
If you have questions, or need help with anything in the library be sure to ask a librarian. At LSU Libraries there are a number of ways to find help:
- Visit the reference desk in room 141 Middleton Library
- Telephone the reference desk at (225) 578-8875 during regular reference hours.
- Email Reference using the online form.
- Use Live Assistance, our live chat service. Click here for the hours and log on form.
