W.E. Westerhoff, H.A. Kemna and W. Boenigk (2008) “The confluence area of Rhine, Meuse, and Belgian rivers: Late Pliocene and Early Pleistocene fluvial history of the northern Lower Rhine Embayment”, Netherlands Journal of Geosciences, 87, pp. 107 - 125. doi: 10.1017/S0016774600024070.