Author
United States. Bureau of Sport Fisheries and Wildlife
5
U.S. Fish and Wildlife Service
4
Wildfowl & Wetlands Trust
2
Wildfowl Trust
2
Audubon Naturalist Society of the Central Atlantic States
1
Audubon Society of the District of Columbia
1
National Wildlife Federation
1
New Jersey. Division of Fish, Game, and Wildlife
1
North American Water Fowl Management Plan
1
U.S. Fish and Wildlife Service. North American Waterfowl and Wetlands Office
1
W.B. Saunders Company
1