Great Lakes Pilotage and Atomic Icebreaker: Hearings Before the Committee on Interstate and Foreign Commerce, United States Senate, Eighty-fifth Congress, Second Session, on S. 2096 and H.R. 7515, to Require Pilots on Certain Vessels Navigating United States Waters of the Great Lakes, and for Other Purposes, and S. 3657, to Authorize the Construction of a Nuclear-powered Icebreaking Vessel for Operation by the United States Coast Guard, and for Other Purposes. May 28, June 17 and 20, 1958