Gerrets, D.A. & J. de Koning 1999, Settlement development on the Wijnaldum-Tjitsma terp. In: J.C. Besteman, J.M. Bos, D.A. Gerrets, H.A. Heidinga & J. de Koning (eds), The excavations at Wijnaldum. Reports on Frisia in Roman and Medieval times. Volume I, Rotterdam/Brookfield, 73-124.