Herngreen et al., 1994
From dinoflaj3
Herngreen, G.F.W., Hartkopf-Fröder, C. and Ruegg, G.H.J., 1994: Age and depositional environment of the Kuhfeld Beds (Lower Cretaceous) in the Alstätte Embayment (w. Germany, e. Netherlands). Geologie en Mijnbouw, v.72, p.375-391.