Connectedness of Opposite-flag Geometries in Moufang Polygons. - Peter Abramenko; Hendrik Van Maldeghem (Eur. J. Comb., 1999)

Combinatorial characterizations of convexity and apartments in buildings. - Peter Abramenko; Hendrik Van Maldeghem (Australas. J Comb., 2006)

Intersections of apartments. - Peter Abramenko; Hendrik Van Maldeghem (J. Comb. Theory A, 2010)