[1]
C. Sánchez-Alonso, X. Ruiz, G. Blanco, ja I. Torre, ”An analysis of the diet of Red-billed Chough Pyrrhocorax pyrrhocorax nestlings in NE Spain, using neck ligatures”, Ornis Fenn, vsk. 73, nro 4, ss. 179–185, joulu 1996.