Benedek and Sarjeant, 1981
From dinoflaj3
Benedek, P.N. and Sarjeant, W.A.S., 1981: Dinoflagellate cysts from the Middle and Upper Oligocene of Tönisberg (Niederrheingebiet): a morphological and taxonomic restudy. Nova Hedwigia, v.35, p.313-356.