Applications for patent on oil-shale lands : consolidated hearings before the Committee on the Public Lands, House of Representatives, Seventy-first Congress, second and third sessions, on H. R. 3754, H. R. 12802, H. R. 13191, H. R. 15002, H. R. 15130, H. R. 15131, H. R. 15132, Parts 1, 2, and 3.