Thomas and Cox, 1988
From dinoflaj3
Thomas, J.E. and Cox, B.M., 1988: The Oxfordian-Kimmeridgian Stage boundary (Upper Jurassic): dinoflagellate cyst assemblages from the Harome Borehole, north Yorkshire, England. Review of Palaeobotany and Palynology, v.56, p.313-326, pl.1-2.