Tockus erythrorhynchus ruahae Kemp & Delport 2002

Kemp & Delport 2002. Comments on the status of subspecies in the red-billed hornbill (Tockus erythrorhynchus) complex (Aves: Bucerotidae), with the description of a new taxon endemic to Tanzania. Annals of the Transvaal Museum, 39 2002: 1-8