Attributes / relations provided by
♦ ¹Lappalainen, A., M. Rask, H. Koponen & S. Vesala, 2001. Relative abundance, diet and growth of perch (Perca fluviatilis) and roach (Rutilus rutilus) at Tvärminne, northern Baltic Sea, in 1975 and 1997: responses to eutrophication? Boreal Env. Res. 6: 107–118
♦ ²Winter feeding ecology and trophic relationships of Oldsquaws and White-winged Scoters on Kachemak Bay, Alaska, Gerald A. Sanger and Robert D. Jones, Jr., Canadian Wildlife Service, 1984