(en) Rexroad C.B. & Furnish W.M., 1964. Conodonts from the Pella Formation (Mississippian), South-Central Iowa. Journal of Paleontology, Vol. 38, No. 4 (Jul., 1964), pages 667-676 (URL stable sur JSTOR).
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(en) Frest T.J. & Strimple H.L., 1977. Praepholidocidaris, a New Echinoid from the Pella Formation (Mississippian) of Iowa (Mississippian) of Iowa. Proceedings of the Iowa Academy of Science, 84(3),98-105 (lire en ligne).
