Medina, C. A., F. Molano, and C. H. Scholtz. “Morphology and Terminology of Dung Beetles (Coleoptera: Scarabaeidae: Scarabaeinae) Male Genitalia”. Zootaxa, vol. 3626, no. 4, Mar. 2013, pp. 455–476, doi:10.11646/zootaxa.3626.4.3.