Listen to Regulations for the order and discipline of the troops of the United States: part I on your phone!
More commonly know as "The Blue Book" written by "Baron von Steuben" this publication was key to organizing the young American military in the Revolutionary War with England. This book served both as a regulation and a how-to manual. Each officer was required to: purchase a copy upon being commissioned, carry it at all times, read it, and use it. (Summary by David Olson)