Michael Williams. An introduction to the world of tractors for younger readers. The many color photographs will please all ages but the text is ideal for 9-14 year olds. Michael Williams tells how the earliest tractors were developed, explains how they work and describes the leading models in tractor history, including the giant prairie busters. He finishes with a look at the models of the 1990's and the use of the computer in the cab. 82 photos, 96 pgs, Hardcover