BOSCH, M. VAN DEN & H. HAGER
Lithostratigraphic correlation of the Rupelian deposits (Oligocene) in the Boom area (Belgium), the Winterswijk area (The Netherlands) and the Lower Rhine District (F.R.G.).
1984. Reprint: Meded. Werkgr. Tert. Kwart. Geol. 21-3; pp. 123-138, 6 fig. Orig. reprint, 4to.