Non Fiction

Non-Fiction is defined as being literature about facts that are verifiable through many other sources. Scientifically. No matter what system your library has chosen to use for cataloguing, you will still need to sort through the massive amount of such publications and place them appropriately.
Two of the most commonly used formats for Cataloguing are: Dewey Decimal and Library of Congress Classification.

 The Dewey Decimal system was first introduced in 1876 and was adopted by the majority of libraries in the following century.
If your library uses Dewey, you might be interested in sites such as: OCLC's Dewey Online which covers the how and what of classifying by Dewey. This is a very effective tutorial in the uses and applications of one of the most widely used classification systems in the world.
Dewey at a Glance is a good cheat-sheet for students and teachers alike.

The Library of Congress Classification system was originally developed in 1897 but did not gain widespread use until 1939. It was primarily intended for use in the United States national library. As such there is a LOT more room for US publications than there is for any other country. There are work-arounds for this problem and LCC is becoming more popular as it has more expansion room than Dewey does.
The Library of Congress has a site Classification that explains and offers assistance on using the system. Many libraries looking at LCC find a bit of help welcome.
Some people find reading LCC difficult. Reading LCC call numbers is a site with guidelines for this.