M. C. FARRIES, R. I. LAMING, P. R. MORKEL, T. A. BIRKS, D. N. PAYNE, and E. J. TARBOX, "Efficient high-gain erbium-doped fiber amplifier pumped with a frequency-doubled Nd:YAG laser,"
in Optical Fiber Communication Conference,
Vol. 5 of 1989 OSA Technical Digest Series
(Optical Society of America, 1989), paper TUG5.