FM 23-5 Basic field manual : U.S. Rifle, Caliber .30, M1, 1940-07-20
"The rifle must be kept clean and free from dirt and properly lubricated with lubricating grease. To obtain its maximum efficiency the following points must be observed...."
Digitized by AHEC (U.S. Army Heritage Collections) http://www.carlisle.army.mil/ahec/
Includes change no. 1, 2, 3, 4, 5 and 6