Havanur, G. H.; Mahale, V. B., Indian Journal of Chemistry, Section A: Inorganic, Physical, Theoretical and Analytical, 1987, vol. 26, # 12, p. 1063 - 1065
Havanur, G. H.; Revankar, V. K.; Mahale, V. B., Indian Journal of Chemistry, Section A: Inorganic, Physical, Theoretical and Analytical, 1988, vol. 27, # 9, p. 803 - 805