Snopková and Samuel, 1982
From dinoflaj3
Snopková, P. and Samuel, O., 1982: Pentagonium obidum nov. gen. et nov. sp. (incertae sedis) from the Upper Eocene of the west Carpathians (the Podunajská Nížina Lowland). Zapadne Karpaty, Seria Paleontologia, v.8, p.131-133, pl.48-50.