Fenton et al., 1980
From dinoflaj2
Fenton, J.P.G., Neves, R. and Piel, K.M., 1980: Dinoflagellate cysts and acritarchs from Upper Bajocian to Middle Bathonian strata of central and southern England. Palaeontology, v.23, no.1, p.151-170, pl.14-16.