European Breeding Bird Atlas 2 (Keller, Verena / Herrando, Sergi / Voříšek, Petr / Franch, Martí / Kipson, Marina / Milanesi, Pietro / Martí, David / Anton, Marc / Klvaňová, Alena / Kalyakin, Mikhail V. / Bauer, Hans-Günther / Foppe)