The disjoint cliques problem Klaus Jansen; Petra Scheffler; Gerhard Woeginger — 1997 RAIRO - Operations Research - Recherche Opérationnelle
Path systems in acyclic directed graphs H. D. O. F. Gronau; W. Just; W. Schade; Petra Scheffler; J. Wojciechowski — 1987 Applicationes Mathematicae