1. E. C. Njau:Ind. J. Theor. Phys.,33, 39 (1985).
2. E. C. Njau:Proc. Indian Natl. Sci. Acad., Part A,51, 985 (1985).
3. E. C. Njau:Proc. Indian Natl Sci. Acad., Part A,53, 746 (1987).
4. E. C. Njau: ICTP, Trieste, Internal Report IC/87/413 (1987), to be published inProc. Indian Natl. Sci. Acad., Part. A.
5. E. C. Njau:Proc. Indian Natl. Sci. Acad., Part A,52, 1237 (1986).