1. V. S. Indurkar and P. K. Patwardhan, BARC Report - 775.
2. M. Bhattacharya and R. Bhattacharya, Ind. J. Pure Appl. Phys. 14 (5) 404.
3. F. C. Ruegg, J. J. Spijkerman and J. R. Devee, Rev. Sci. Instr. 36, no. 3.
4. P. J. Ouseph et al., Ind. J. Pure Appl. Phys. 14 (9) 779.