... Cygnus cygnus cygnus in central Scotland. Pp. 161–169 in Proceedings of the Second International Swan Symposium, Sapporo, Japan, 1980 (G. V. T. Matthews and M. Smart, eds.). Slimbridge, UK: International Waterfowl Research Bureau ...
... Cygnus cygnus " whooper swan " Ryzhikov , K M .; Kazlauskas , Orchipedum tracheicola cygni new form J .; and Dalia , G. G. , 1968 a , 97-105 Cotylurus cornutus cygni all from Latvia new form Cygnus cygnus " lebed - klikun ...