Michael A. Bender, Dana Ron. Testing Acyclicity of Directed Graphs in Sublinear Time. In Ugo Montanari, José D. P. Rolim, Emo Welzl, editors, Automata, Languages and Programming, 27th International Colloquium, ICALP 2000, Geneva, Switzerland, July 9-15, 2000, Proceedings. Volume 1853 of Lecture Notes in Computer Science, pages 809-820, Springer, 2000. [doi]