De Vernal et al., 1992
From dinoflaj3
de Vernal, A., Londeix, L., Mudie, P .J., Harland, R., Morzadec-Kerfourn, M.T., Turon, J.-L. and Wrenn, J.H., 1992: Quaternary organic-walled dinoflagellate cysts of the North Atlantic Ocean and adjacent seas: ecostratigraphy and biostratigraphy. In: Head, M.J. and Wrenn, J.H. (editors), Neogene and Quaternary dinoflagellate cysts and acritarchs, p.289-328, pl.1-8; American Association of Stratigraphic Palynologists Foundation, Dallas, U.S.A.