Mcadams, N. E., Adrain, J. M., & Karim, T. S. (2018).

The pliomerid trilobite Ibexaspis and related new genera, with species from the Early Ordovician (Floian; Tulean, Blackhillsian) of the Great Basin, western USA

. Zootaxa, 4525(1), 1–152. https://doi.org/10.11646/zootaxa.4525.1.1