P.J. Felder, E. Keppens, B. Declercq, S. Normand, and M. Streel, “Faunal/floral and isotopic responses to Milankovitch precession cycles and environmental changes in the upper Gulpen Formation (Upper Maastrichtian) at the CBR-Lixhe and ENCI-Maastricht bv quarries”, njg, vol. 82, pp. 275-281, Aug. 2003.