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♦ ¹Dietary importance of various prey fishes for pikeperch Sander lucioperca (L.) in large shallow lake Võrtsjärv (Estonia), Peeter Kangur, Andu Kangur, and Külli Kangur, Proc. Estonian Acad. Sci. Biol. Ecol., 2007, 56, 2, 154-167
♦ ²Robert Gwiazda, Dariusz Bukaciński, Grzegorz Neubauer, Marcin Faber, Jacek Betleja, Magdalena Zagalska-Neubauer, Monika Bukacińska & Przemysław Chylarecki, Diet composition of the Caspian Gull (Larus cachinnans) in inland Poland: effects of breeding area, breeding stage and sympatric breeding with the Herring Gull (Larus argentatus), Ornis Fennica 88:80–89. 2011