JournalsemVol. 53, No. 3Volume 53, No. 3 (1998) Elemente der Mathematikpp. 89–106On Nonconvex Caustics of Convex BilliardsOliver Knillpp. 107–111Teaching the Independence of Xˉ\bar XXˉ and S2S^2S2Wiebe R. Pestmanpp. 112–118Regular Hexagons Associated to Triangles with Equal CentroidsZvonko Čerinpp. 119–125Zur Kurvendiskussion der PotenzsummenpolynomeDietmar Treiberpp. 126–130Aufgabenpp. 131–132Bücher und Computersoftware