References
Romein, A.J.T., Willems, H. & Mai, H. 1996. Calcareous nannoplankton of the Geulhemmerberg K/T boundary section, Maastrichtian type area, the Netherlands. In: Brinkhuis, H. & Smit, J. (eds.), The Geulhemmerberg Cretaceous/Tertiary boundary section (Maastrichtian type area, SE Netherlands). Geologie en Mijnbouw, 75: 231-238.