Doweld, Alexander B. 2016. “Protaeropsis, a New Replacement Generic Name for fossil Sphenaster Jeffery, 1999 (Echinoidea: Spatangida) nec Wilcoxon, 1970 (Protista: Haptomonada)”. Zootaxa 4139 (3). Auckland, New Zealand:421–423. https://doi.org/10.11646/zootaxa.4139.3.6.