Hogg and Bailey, 1997
From dinoflaj3
Hogg, N.M. and Bailey, D.A., 1997: Prolixosphaeridiopsis spissus gen. et comb. nov. for the dinoflagellate cyst Cleistosphaeridium spissum McIntyre and Brideaux 1980. Journal of Micropalaeontology, v.16, no.1, p.50.