1. Armitage, J. D. and A. Lohmann, 1964, Paper presented at the ICO Conference in Sydney; see also Opt. Acta 12: (1965) 185.
2. R.R. Baldwin 1968, U.S. Pat. 3.512.891.
3. A wavefront shearing interferometer
4. A New Technique for the Evaluation of the Quality of Plane Surfaces