Brehms Tierleben 2.2 page 430 Corvultur crassirostris, 1879

Thick-billed raven (corvus crassirostris). Illustration by robert kretschmer (?) from brehms tierleben (english title: brehm's life of animals). Description under the picture reads: erzrabe (corvultur crassirostris). ⅙ natürl. Größe. Date: 1879.