Ornan Ori Gerstel. On limited wavelength conversion in optical ring networks. In Marios Mavronicolas, Michael Merritt, Nir Shavit, editors, Networks in Distributed Computing, Proceedings of a DIMACS Workshop, New Brunswick, New Jersey, USA, October 27-29, 1997. Volume 45 of DIMACS Series in Discrete Mathematics and Theoretical Computer Science, pages 91-96, DIMACS/AMS, 1997.