English
Reference
Peter Dreyer, Carl Gunnar Gustavsson (2010): Photographie documentation of a Swan Goose x Snow Goose Anser cygnoides x Anser caerulescens hybrid and its offspring with a Barnacle Goose (Branta leucopsis) - a unique three-species cross – Ornithologischer Anzeiger – 49_1: 41 - 52.
