Klug, C.; Kröger, B.; Rücklin, M.; Korn, D.; Schemm-Gregory, M.; De Baets, K.; Mapes, R. H. (2008). Ecological change during the early Emsian (Devonian in the Tafilalt (Morocco), the origin of the Ammonoidea, and the first African pyrgocystid edrioasteroids, machaerids and phyllocarids.
Palaeontographica, Abt. A. 283(4-6): 83-176.