Streng et al., 2002
From dinoflaj2
Streng, M., Hildebrand-Habel, T. and Willems, H., 2002: Revision of the genera Sphaerodinella Keupp and Versteegh, 1989 and Orthopithonella Keupp in Keupp and Mutterlose, 1984 (Calciodinelloideae, calcareous dinoflagellate cysts). Journal of Paleontology, v..76, p.397-407.
