SUMMERS, Ron W. Gulls associating with flocks of Brent Geese Branta bernicla on farmland. Wildfowl, [S. l.], v. 43, p. 96–98, 1992. Disponível em: https://tidsskrift.dk/Wildfowl/article/view/155371. Acesso em: 15 apr. 2026.