A.A. Slupik, F.P. Wesselingh, A.C. Janse, and J.W.F. Reumer, “The stratigraphy of the Neogene-Quaternary succession in the southwest Netherlands from the Schelphoek borehole (42G4-11/42G0022) – a sequence-stratigraphic approach”, njg, vol. 86, pp. 317-332, Dec. 2007.