MULLINS, Gary L. 2002 (May 1) Revision of acritarchs and prasinophyte algae from the lower Silurian of Belgium Journal of Micropalaeontology 21(1): 87-94 new combs. Buedingiisphaeridium parveroquesi, Dictyotidium deflandrei, Helosphaeridium echinodermum and Multiplicisphaeridium pentagonale