Call Numbers and the Library of Congress Classification System

The Dewey Decimal Classification System

The Dewey Decimal Classification (DDC) is a system for arranging items in a library.  It is the most widely used system and is the one often used by most public libraries and some small academic libraries.  This system divides materials into ten main groups using a combination of numbers.   These ten main groups are divided into specific fields.   When a field needs to become even more specific, decimals are use to represent these specific areas.  

Main Dewey Decimal Classification groups

000-099   Generalities (encyclopedias, bibliographies, periodicals, journalism)

100-199   Philosophy and related disciplines (psychology, logic, etc.)

200-299   Religion

300-399   Social sciences (economics, sociology, civics, law, education, vocations, customs)

400-499   Language (language, dictionaries, grammar)

500-599   Pure sciences (mathematics, astronomy, physics, chemistry, geology, biology, zoology)

600-699   Technology and applied sciences (medicine, engineering, agriculture, business, radio)

700-799   The arts (architecture, sculpture, painting, music, photography, recreation)

800-899   Literature (novels, poetry, plays, criticism)

900-999   Geography, history, and related disciplines

For example, class 600-699, Technology and Applied Sciences, is subdivided into ten special classes.   The class 610-619 contains Medical Science/Medicine and is subdivided into classes such as Human Anatomy, Human Physiology, Promotion of Health, Pharmacology, and Experimental Medicine.   Each of these subdivisions is further divided.   For example, materials on Diseases are listed under 616 with materials covering Diabetes being listed under 616.462 and materials covering Heart Disease are listed under 616.12.

Using the Dewey Decimal Classification System

Your local public library probably uses the Dewey Decimal Classification System to organize its materials so it is important to have a general understanding of how this system works. (In addition to the call number, it is important to note which Item Location is indicated in the catalog:   Stacks, Reference, Audiovisual, Special Collections, etc.)

The call number on the spine of an item usually contains two or three lines. Each line should be read separately. A typical call number might read as follows:

(Line 1) 610.736      OR      (Line 1)  610.736
(Line 2) .L61                       (Line 2)  L
(Line 3) 1981       

Line 1.  Materials are shelved by the whole numbers first, then by the numbers following the decimal point. The numbers to the left of the decimal point are whole numbers. Numbers to the right of the decimal point are not and are shelved digit by digit rather than by the entire number. (This is the part of the call number that is confusing to many library users.)  For example, 607.2 is shelved before 607.25 because 607.2 really means 607.20.  Since 607.20 precedes 607.25, it would be shelved first. If you become confused, simply add a "mental" zero to a single digit when comparing it to a double digit.

The call numbers below are in correct order from top to bottom.

607
607.2
607.25 

Line 2.  The second line usually refers to the author of the item.  Some libraries will list the first few letters of the author's last name on this line.   In these cases, items with the same first line will be shelved in alphabetical order by author's last name.  If there is more than one item with the same first line of the call number and author, then the materials are shelved in order the title of the item. 

Many libraries use the Library of Congress Cutter Tables for this second line. The Cutter is a combination of letters and numbers usually representing the author's last name.  The Cutter is preceded by a decimal point and are read one digit at a time.  

Line 3.  If the call number has three lines, this third line will usually be a four digit number which reflects the date of publication (i.e., 1980, 1986).  If the preceding lines are identical, then the items will be shelved in chronological order by the date of publication.

Additional Resources:

Dewey Decimal System Homepage OCLC

Finding materials on the shelf can be confusing at first.  Don't be embarrassed to ask a Librarian for help. That is why we are here!  

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United States Government Printing Office

The United States Government Printing Office (G.P.O.) is the world's largest publisher, publishing everything from the Economic Report of the President to colorful posters put out by the National Park Service. These publications are issued by Congress, government agencies from all three branches, and commissions.   They are available electronically in addition to paper or microform. GPO's main mission is to ensure the American public has access to Government information.   

What Type of Information is Available as Government Documents?

The federal government collects information on a wide variety of topics.  The federal government sponsors a variety of research studies and tracks statistics on a wide array of subjects.  If you are needing statistical or research information, government documents can be a gold mine of information.

Federal Depository Library Program

The Federal Depository Library Program was established by Congress to ensure that the American people have access to its Government's information.   The mission of the FDLP is to disseminate information products from all three branches of the Government to more than 1,250 libraries nationwide. Libraries that have been designated as Federal depositories maintain these information products as part of their existing collections and are responsible for assuring that the public has free access to the material provided by the FDLP.

 Examples of Federal Government Documents

Some examples of commonly used federal government documents are:

• Monthly Catalog - GPO produces an index to government documents that provides access via author, title, series/report, contract number, or title/keyword--current indexes are available online at https://catalog.gpo.gov/F?RN=190935102.
• Congressional Quarterly Weekly Report - This commercial publication reports on activities in Congress and may be consulted to learn the status and/or date of legislation--once you have this information you can search for the document itself.
• Statistical Abstract of the United States - Standard summary of statistics on the social, political, and economic organization of the United States.  Designed as a convenient volume for statistical reference and as a guide to other statistical sources.
• U.S. Industrial Outlook - Forecasts for selected manufacturing and service industries .

Using Superintendent of Documents Numbers

Government documents are arranged according to the Superintendent of Documents Classification System.  This explanation of what these numbers mean will help you in finding appropriate materials. 

AE 1.113:2/991

AE - represents the Author Symbol, the issuing agency (in this example, the National Archives and Records Administration).

1. - represents the subordinate office or bureau within agency and/or department. 1 is the parent organization and will always be followed by a period. 

113: - represents the series number (in this example, 113 is the general information leaflet series). This is always followed by a colon and occasionally there are numbers for new series closely related to existing series -  5/a: or 5/2.

2/ A - represents the unique item number.

991 - represents the date of revision (in this example, 991 = 1991). If this were a serial, the number may represent a volume or issue number.

Additional Resources:

Learning SuDocs Call Numbers Michigan State University

U.S. SuDoc and Agency List University of Illinois at Urbana-Champaign University Library

If you need assistance at any time using Government Documents, ask the Librarian for assistance.

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What is the Library of Congress Classification System and how does it help you?

One of the major responsibilities of a library is to organize its materials (books, videos, DVDs, etc.) so that users-that is you- can find the materials that you need. To do this, libraries assign a "call number" to each item. This call number tells you both where the book can be found and what the book is about. The form and sequence of these call numbers is set by a "classification system." "Classification system" is simply the term used to describe the system that is used to create these call numbers.

There are two very common classification systems, the Library of Congress Classification System (LCC) and the Dewey Decimal Classification System (DDC). Most of the larger college and university libraries use the LCC while many public libraries tend to use the DDC. In the LCC, each capital letter or combination of capital letters represents one subject, for example, DA represents the history of England. The numbers following the letters then indicate where the item would be found on the shelf. The information below tells you how to read and use these numbers.

Finding books in your library. To find books in your library, use the library's online " catalog." A catalog is nothing more than a list of all of the materials held in a library. At Henderson Community College the online catalog is called Primo. Primo is the most common online catalog used in Kentucky's public colleges and universities. Extended instructions on how to use Voyager can be found in the Learning Unit, "Using Primo".

When using Primo, you will notice that it provides both an item's call number and "location." While the instructions below explain how to read and use LCC call numbers, the "location" tells you where in the library that item can be found. Each library has a number of locations. Typical locations include: encyclopedias and dictionaries are found in the Reference Collection; books that can be checked out are found in the Book Stacks; videos and DVDs can be found in the Audiovisual Collection; newspapers, magazines, and journals can be found in the Periodicals area. When looking for library materials, make sure that you note both the location and the call number of the desired item(s).

How do you read and use the LCC call numbers? The system organizes materials in alpha-numeric order. The call number on the spine of an item contains at least three lines. Each line should be read separately. A typical call number might read as follows:

     
     (Line 1) BS 617     
     (Line 2) .L61
     (Line 3) G3
     (Line 4) 1981

Line 1. The first line always includes a single letter or a combination of letters. When shelved, single letters are arranged first. Double letters follow single letters. The letters below are in correct order from top to bottom.
          P
          PN
          PR
          PS
          PZ

These letters may then be followed by numbers. Materials are shelved in numerical order from the lowest number to the highest number. The call numbers below are in correct order from top to bottom.

          BF 31
          BF 310
          BF 3105

Some numbers in this line have a decimal point. Here are some examples.

          BF 30.5
          QC 719.8

Materials are shelved by the whole numbers first, then by the numbers following the decimal point.

          BF 607
          BF 607.2
          BF 6072
          BF 6072.5

Line 2. Line two usually begins with a decimal point followed by a letter. Materials are shelved alphabetically by the letter. A number always follows the letter. When line two begins with a decimal point, the numbers are decimals -- not whole numbers. Therefore, numbers in line two are filed digit by digit rather than by the whole number. (This is the part of the call number that is confusing to many library users.)

For example, .G39 is shelved before .G4 because .G4 really means .G40. Since .G39 precedes .G40, .G39 would be shelved first.

The number .B765 is filed before .B77 because .B77 is .B770. If you become confused, simply add a "mental" zero to a single digit when comparing it to a double digit.

The call numbers below are in correct order from top to bottom.

          BF 706 .A2
          BF 706 .A276
          BF 706 .A281
          BF 706 .A29

Line 3. Many call numbers are only three lines long. If a fourth line is added, line 3 will follow the same pattern as line 2 as is it actually a continuation of the second line that began with a decimal point. Although the third line will not begin with a decimal point, the numbers are decimals -- not whole numbers. These numbers are filed like those in line two, digit by digit. The call numbers below are in correct order from top to bottom.

          BF 706 .A2 G49
          BF 706 .A2 G5
          BF 706 .A2 G513
          BF 706 .A2 G52
          BF 706 .A2 G521

If the call number has only three lines, this third line will usually be a four digit number which reflects the date of publication (i.e., 1980, 1986).  If the preceding lines are identical, then the items will be shelved in chronological order by the date of publication.

Additional Resources:

The Library of Congress Classification System The Online Library Learning Center

The Library of Congress Classification Outline Library of Congress

Finding materials on the shelf can be confusing at first.  Don't be embarrassed to ask a Librarian for help.