Paul et al., 1994
From dinoflaj3
Paul, C.R.C., Mitchell, S.F., Marshall, J.D., Leary, P.N., Gale, A.S., Duane, A.M. and Ditchfield, P.W., 1994: Palaeoceanographic events in the Middle Cenomanian of northwest Europe. Cretaceous Research, v.15, p.707-738.