K. Linthout, H. Paulick, and J.R. Wijbrans, “Provenance of basalt blocks from Roman sites in Vleuten-De Meern (the Netherlands) traced to the Tertiary Siebengebirge (Germany): a geoarchaeological quest using petrological and geochemical methods”, njg, vol. 88, pp. 55 - 74, Mar. 2009.