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Scott, D. K. Functional aspects of the pair bond in winter in Bewick's swans (Cygnus columbianus bewickii). Behavioral Ecology and Sociobiology. 1980, 7 (4): 323–327. S2CID 32804332. doi:10.1007/BF00300673(英语).
Russell, Bertrand. On Induction. The Problems of Philosophy. London: Williams and Norgate. 1912 [2016-01-20]. ISBN 9781605200255. (原始内容存档于2019-09-15) (英语).
Wood, Kevin A.; Ham, Phoebe; Scales, Jake; Wyeth, Eleanor; Rose, Paul E. Aggressive behavioural interactions between swans (Cygnus spp.) and other waterbirds during winter: a webcam-based study. Avian Research. 2020-08-07, 11 (1): 30. ISSN 2053-7166. doi:10.1186/s40657-020-00216-7(英语).