Smit, J. & Zachariasse, W.J. 1996. Planktic foraminifera in the Cretaceous/Tertiary boundary clays of the Geulhemmerberg (Netherlands). In: Brinkhuis, H. & Smit, J. (eds.), The Geulhemmerberg Cretaceous/Tertiary boundary section (Maastrichtian type area, SE Netherlands). Geologie en Mijnbouw, 75: 187-191.