Conservation of natural resources -- North Dakota. : Comprehensive conservation plan [electronic resource] : Des Lacs National Wildlife Refuge, J. Clark Salyer National Wildlife Refuge, Upper Souris National Wildlife Refuge / prepared by U.S. Fish and Wildlife Service.
Conservation of natural resources -- Pennsylvania. : H.R. 1616 and H.R. 1964 : legislative hearing before the Subcommittee on National Parks, Recreation, and Public Lands of the Committee on Resources, U.S. House of Representatives, One Hundred Eighth Congress, first session, June 17, 2003.