The Library of Congress , located in Washington, D.C. is one of the largest libraries in the world, comprised of materials in all formats, languages and subjects. The classification system was designed to group library materials of similar subject concentration together and is used by many major library collections. The Library of Congress call number system is an alpha-numeric sytem. To read the call number, simply note the first letter or letters of the call number.
Numbers follow the initial letter or letters.
These numbers are read as whole numbers. The third element or line of the call number is the one which gives people the most trouble. This line is called the Cutter number and it is a letter followed by a decimal number. Sometimes there are two Cutter number lines. Once again, regard the Cutter number alphabetically and then by decimal number.