Lansford Warren Hastings authored, The Emigrants' Guide to Oregon and California. Reed and Donner purchased his book in Springfield and referenced the information it contained in to make decisions in their journey to California. Hasting's book was the main reason the Donner Party chose to take the Hastings Cutoff in order to save time. Their decision, however, caused them to lose time and led to their entrapment in the Sierra Nevadas.
The Perilous Journey of the Donner Party