Källander, Hans. 2013. “Commensal Use of Mute Swans Cygnus Olor by Common Coot Fulica Atra and of Canada Geese Branta Canadensis by European Wigeon Anas Penelope”. Ornis Svecica 23 (2). Lund, Sweden:108–110. https://doi.org/10.34080/os.v23.22580.