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, R J Gordon and Z Ikonic
Superlattices and Microstructures 9, 43-46 (1991).
R J Gordon and G P Srivastava
Superlattices and Microstructures 9, 47-50 (1991).