How to use the Library of Congress Classification System to Browse by Subject
Say you want to find a book on the history of Rome. Start at the Library of Congress Classification Outline (http://www.loc.gov/catdir/cpso/lcco/ or at the Research Center Desk) to find the subject you wish to browse.
1. First, use the outline to find the class that encompasses your subject. The history of Rome looks like it will fall under class D. Select it to view the subclasses within class D.
2. This next screen of the Classification Outline shows the different subclasses within the D class. Select the appropriate subclass. Books on the Greco-Roman world are in subclass DE. Select the subclass to view the categories within the class:
3. This next portion of the outline shows a number that may have one or more digits that corresponds with the one to four digits that follow the subclass letter(s). This line is read numerically. A call number with a smaller number is shelved before one that has a larger number. Some of these numbers may be divided by a point: these are also read numerically (smaller numbers are shelved before larger numbers). The books categorized in this subject will all be shelved within this range. Basic history will be shelved between DE80 and DE100.
4. Write down (or otherwise remember) the range of call numbers (here DE80-100) and use the signs on the end of each shelf to find the correct shelf. Remember that classes are arranged alphabetically in the stacks. The subclasses are likewise arranged alphabetically within their class. The next portion of the call number is a one to four digit number, with smaller numbers shelved before larger numbers. According to this shelf sign, DE80-100 will be on this shelf, as the DE subclass alphabetically falls between DD and DG:
Find the category you are looking for, and have fun.