Radmacher et al., 2014
From dinoflaj3
Radmacher, W., Tyszka, J. and Mangerud, G., 2014: Distribution and biostratigraphical significance of Heterosphaeridium bellii sp. nov. and other Late Cretaceous dinoflagellate cysts from the southwestern Barents Sea. Review of Palaeobotany and Palynology, v.214, p.29-40, pl.1.