1. Cohen, L.G., and Lin, Chinlon: ‘Transmission measurements of zero material dispersion in optical fibers’, Post-deadline paper PD 5.12, 1977 IEEE/OSA CLEA, Washington, D.C 1977 June, 1–3),(Digest in IEEE J. Quantum Electron, 1977, QE-13, pp. 91–92); alos Appl. Opt., 1977, 16, pp. 3136-3139, and unpublished work