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♦ 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
♦ ²Energy flow of a boreal intertidal ecosystem, the Sylt-Rømø Bight, Dan Baird, Harald Asmus, Ragnhild Asmus, Mar Ecol Prog Ser 279: 45–61, 2004