"We tie knots and bind up words in double meanings, and then try to untie them."
-- Seneca, Epistulae ad Lucillium.
You may think of the card catalog as the most important single reference source in the library, but are you aware of its limitations? It indexes only the general subjects of books. It does not index parts of most books, nor does it provide access to periodical articles. In many libraries the card catalog does not include government documents. And it does not give much help in evaluating the books it lists.
A card catalog is usually simple to use if you need a particular book and know its author or title. You simply look up the author or title and copy down its call number. The big difficulty with the card catalog comes when you try to find what books the library has on a particular subject. Then you must cope with the special language of subject headings, which is significantly different from spoken English.
There are two main ways to identify the proper subject headings for your topic. One way is to use the subject tracings on catalog cards. Earlier in this text we searched the encyclopedias and found a reference to S. Feshbach Television and Aggression. Naturally, you would go to the card catalog to see if your library has it. When you look it up, note the subject tracing "Violence in television" printed at the bottom of the card (FIGURE 2.1), and then look for other books under that same subject heading.
There are problems, however, with this approach. First of all, the Feshbach book was selected as one which could give you background in television and aggression, but it may or may not be helpful with "violence in television news." Therefore, the headings assigned to this book may not lead you to other books that focus precisely on the aspects you