1. L. R. Baker, Optica Acta., 18, 81, (1971).
2. Proc. S. P. I. E. “On Assessment of Imaging System”, Vol-98 (1977). edited by W. A. Bellingham.
3. O. H. Schade, NBS Cir No. 526, 231 (1954).
4. A. Cox, NBS Cir No. 526, 267 (1954).
5. R. V. Schack, NBS Cir No. 526, 275 (1954).