Klaus, S.; Bauer, H.-G.: Tetraogallus caucasicus Caucasian Snowcock. In: European Breeding Bird Atlas 2: Distribution, Abundance and Change, p. 72 - 72 (Eds. Keller, V.; Herrando, S.; Voříšek, P.; Franch, M.; Kipson, M. et al.). European Bird Census Council & Lynx Edicions, Barcelona (2020)

Klaus, S.; Bauer, H.-G.: Lyrurus mlokosiewiczi Caucasian Black Grouse. In: European Breeding Bird Atlas 2: Distribution, Abundance and Change, p. 96 - 96 (Eds. Keller, V.; Herrando, S.; Voříšek, P.; Franch, M.; Kipson, M. et al.). European Bird Census Council & Lynx Edicions, Barcelona (2020)

Ottens, G.; Bauer, H.-G.: Estrilda astrild Common Waxbill. In: European Breeding Bird Atlas 2: Distribution, Abundance and Change, p. 781 - 781 (Eds. Keller, V.; Herrando, S.; Voříšek, P.; Franch, M.; Kipson, M. et al.). European Bird Census Council & Lynx Edicions, Barcelona (2020)