References
- Cobb, P. W. and Moss, F. K, J. Franklin Inst., 205. 831 (1928); British Standards 1384 and 1613.
- Higgins, G. C. and Jones, L. A., J.S.M.P.T.E., 58, 277. (1952).
- Selwyn, E. W. H., Phot. Journal, 88B, 6, 46, (1948).
- Hoichkiss, R. N., Washer, F. E. and Rosberry F. W., J. Opt. Soc. Amer., 41. 600, (1951).