Edge disjoint cliques in graphs. In: Halász G, Lovász L, Miklós D, Szőnyi T, editors. Sets, graphs and numbers : a birthday salute to Vera T. Sós and András Hajnal. Amsterdam: North-Holland; 1992. p. 357-63. (Colloquia mathematica Societatis János Bolyai; no 60).
How many edges should be deleted to make a triangle-free graph bipartite? In: Halász G, editor. Sets, graphs and numbers : a birthday salute to Vera T. Sós and András Hajnal. Amsterdam: North-Holland; 1992. p. 239-63. (Colloquia mathematica Societatis János Bolyai; no 60).