Vijay V. Vazirani, Mihalis Yannakakis. Pfaffian Orientations, 0/1 Permanents, and Even Cycles in Directed Graphs. In Timo Lepistö, Arto Salomaa, editors, Automata, Languages and Programming, 15th International Colloquium, ICALP88, Tampere, Finland, July 11-15, 1988, Proceedings. Volume 317 of Lecture Notes in Computer Science, pages 667-681, Springer, 1988.
Abstract is missing.