P. Leupen, “V.D. van Aalst, K.N. Ciggaar, Byzantium and the Low Countries in het tenth century. Aspects of art and history in the Ottonian era”, BMGN-LCHR, vol. 103, no. 1, pp. 62–63, Jan. 1988, doi: 10.18352/bmgn-lchr.2902.