Invitation Paper (C.P. Alexander Fund): History of Bacillus thuringiensis Berliner research and development
Authors: Beegle, C.C., Yamamoto, T.
Journal, Volume, Year: Canadian Entomologist, volume 124:587-616, 1992
Thorough review article that traces development of Bt from discovery to very beginnings of transgenic Bt usage.
This article is useful as an overview.