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.
A Umerski and G P Srivastava
Surf Rev and Lett 1, 495-499 (1994)
G P Srivastava
Surf Rev and Lett 1, 677-680 (1994).
A Umerski and G P Srivastava
Surf Rev and Lett 1, 681-684 (1994).