If you have trouble locating any of these papers please contact an author for a reprint. A few of the later G.P. Srivastava Group papers are available as on line Postscript documents.
G P Srivastava, J L Martins and A Zunger
Phys Rev B 31, 2561-2564 (Rapid Commun) (1985).
G P Srivastava, J L Martins and A Zunger
Phys Rev B 36, 2902-2905 (1987).
G P Srivastava, J L Martins and A Zunger
Phys Rev B 38, 12694 (1988).