Adrain, J.M., Westrop, S.R., Karin, T.S., Landing, E., 2014. Trilobite Biostratigraphy of the Stairsian Stage (upper Tremadocian) of the Ibexian Series, Lower Ordovician, Western United States. Memoirs of the Associaiton of Australasian Palaeontologists  45, 167?214.

Adrain, J.M., Lee, D.C., Westrop, S.R., Chatterton, B.D.E., Landing, E., 2003. Classification of the Trilobite Subfamilies Hystricurinae and Hintzecurinae subfam. nov., with New Genera from the Lower Ordovician (Ibexian) of Idaho and Utah. Memoirs of the Queensland Museum 41, 55-105.

Adrain, J.M., Westrop, S.R., Landing, E., Fortey, R.A., 2001. Systematics of the Ordovician Trilobites Ischyrotoma and Dimeropygiella, With Species from the Type Ibexian Area, Western USA. Journal of Paleontology 75, 947-971. doi:10.1666/0022-3360(2001)075<0947:SOTOTI>2.0.CO;2