Tripathi; Singh; Saxena
Indian Journal of Chemistry - Section B Organic Chemistry Including Medicinal Chemistry, 1990 , vol. 29, # 9 p. 865 - 869

A. H. Robins Company, Inc.
Patent: US4151285 A1, 1979 ;

Boswell Jr.; Welstead Jr.; Duncan Jr.; Johnson; Funderburk
Journal of medicinal chemistry, 1978 , vol. 21, # 1 p. 136 - 139