Scott, E., Visser, J. D., Yetman, C. A., Yetman, C. A., Oliver, L., & Broadley, D. G. (2013). Revalidation of Pyxicephalus angusticeps Parry, 1982 (Anura: Natatanura: Pyxicephalidae), a bullfrog endemic to the lowlands of eastern Africa. Zootaxa, 3599(3), 201–228. https://doi.org/10.11646/zootaxa.3599.3.1