H.S.M. Jansen, J. Huizer, J.W.A. Dijkmans, C. Mesdag, and J.E. van Hinte. “The Geometry and Stratigraphic Position of the Maassluis Formation (western Netherlands and Southeastern North Sea)”. Netherlands Journal of Geosciences, vol. 83, June 2004, pp. 93 -99, doi:10.1017/S0016774600020060.