La sonnambula used themes from a Vincenzo Bellini opera that had a libretto by whom?
I Capuleti e i Montecchi:  The libretto by Felice Romani was a reworking of the story of "Romeo and Juliet" for an opera by Nicola Vaccai called "Giulietta e Romeo" and based on the play of the same name by Luigi Scevola written in 1818, thus an Italian source rather than taken directly from William Shakespeare.
i don't know