Donald C. S. Allison, Ritu Chadha. An O(N log N) expected time merge heuristic for the planar ETSP. In Arthur M. Riehl, editor, Computer Trends in the 1990s - Proceedings of the 1989 ACM 17th Annual Computer Science Conference, Louisville, Kentucky, USA, February 21-23, 1989. pages 472, ACM, 1989. [doi]