1. R.R. Monchamps, J. Cryst. Growth, 11, 310 (1971)
2. J.J. Derby, R.A. Brown, J. Cryst. Growth, 83, 137 (1987)
3. S. Berkman, M.T. Duffy, H.E. Temple, US Patent, 4,356, 152 (26 Oct. 1982)
4. S. Berkman, M.T Duffy, Kyong Min Kim, G.W Cullen, US Patent, 4,099,924 (11 July 1978)
5. J.J.L.E. Brissot, US Patent, 4,125,425 (14 Nov. 1978)