Vessel traffic control : hearings before the Subcommittee on Coast Guard and Navigation of the Committee on Merchant Marine and Fisheries, House of Representatives, Ninety-fourth Congress on vessel traffic control: investigating the total problem of vessel traffic control and the particular problems encountered in certain areas, June 26, 1975--Washington, D.C., June 27, 1975--New York, N.Y., July 7, 1975--Philadelphia, Pa., October 3, 1975--New Orleans, La., September 21 and 22, 1976--Washington, D.C. : Coast Guard activities in the upper Great Lakes: oversight of the activities of the Coast Guard pertaining to the facilities and operations in the upper Great Lakes, July 16, 1976--Sault Sainte Marie, Mich