D. L. FRANZEN, G. W. DAY, B. L. DANIELSON, E. M. KIM, and G. E. CHAMBERLAIN, "Results of an interlaboratory measurement comparison among fiber manufacturers to determine attenuation, bandwidth, and N.A. of graded-index optical fibers,"
in Integrated Optics and Optical Fiber Communication, M. Barnoski, T. Giallorenzi, J. Goell, J. Midwinter, and Y. Suematsu, eds.,
OSA Technical Digest
(Optical Society of America, 1981), paper TUK1.