Edmund Ihler. Bounds on the quality of approximate solutions to the Group Steiner Problem. In Rolf H. Möhring, editor, Graph-Theoretic Concepts in Computer Science, 16rd International Workshop, WG 90, Berlin, Germany, June 20-22, 1990, Proceedings. Volume 484 of Lecture Notes in Computer Science, pages 109-118, Springer, 1990.
Abstract is missing.