GPS Land Navigation (Book) by Michael Ferguson

Thorough, easy to understand treatment of GPS system for navigation, with info on compasses, maps, GPS hardware, how they work together. Also the various coordinate systems, use of GPS with and without a map, and what to do if hardware stops working. Great reference, too: appendices list 1000s of coordinates: highest peak in every US county, intersections of every US Interstate/Hwy. 270 pages.