TY  - RPRT
TI  - A model of the productivity of the mallard duck
AU  - Douglas H. Johnson
AU  - Donald W. Sparling
AU  - Lewis M. Cowardin
PY  - 1987
DO  - 10.1016/0304-3800(87)90100-1
UR  - https://pubs.usgs.gov/publication/1001541
ID  - 1001541
ER  -