Duck feeding and duck stamp legislation : hearings before the Subcommittee on Fisheries and Wildlife Conservation of the Committee on Merchant Marine and Fisheries, House of Representatives, Eighty-Fifth Congress, first session on H.R. 6959, a bill to authorize the Secretary of the Interior to cooperate with federal and non-federal agencies in the augmentation of natural food supplies for migratory waterfowl : H.R. 6691, a bill to authorize a 10-year program for acquiring national migratory-bird refuges and areas : H.R. 5817, a bill to authorize for each fiscal year an appropriation into the Migratory Bird Conservation Fund, June 6 and 7, 1957.