E. Wijnker, T.J. Bor, F.P. Wesselingh, D.K. Munsterman, H. Brinkhuis, A.W. Burger, H.B. Vonhof, K. Post, K. Hoedemakers, A.C. Janse, and N. Taverne. “Neogene Stratigraphy of the Langenboom Locality (Noord-Brabant, the Netherlands)”. Netherlands Journal of Geosciences, vol. 87, Aug. 2008, pp. 165 -80, doi:10.1017/S0016774600023209.