Bellini 's first opera is also the most complicated when it comes to reconstructing the composer's various versions and revisions of it. A major step forward came in 2001 when a series of hitherto unknown sources housed in the Fondo Mascarello in the library of the Milan College of Music allowed many previous gaps to be filled and a number of questions to be answered. Above all it enabled knowledge of Adelson e Salvini to be revised radically. In its sole authentic complete version, Adelson e Salvini is a French-style opera semiseria in which musical numbers are separate from spoken dialogue. Adelson e Salvini is surprisingly fresh in approach and heralds the great things that would later come from its composer.