There are many, many studies of Puccini's life and work and of BUTTERFLY itself . BLO Artistic Advisor John Conklin recommends a few to start off with...
by Conrad Wilson
Phaidon Press London 1997 (20th Century Composers Series)
Well written and organized overview of both Puccini's controversial and often difficult personality and his still rather controversial place in the ranks of the very greatest opera composers. With many very interesting illustrations