AF.136 DIGITAL SINGLE-OPERATOR CHOLANGIOSCOPY IN TREATING DIFFICULT BILIARY STONES: RESULTS FROM A MULTI-CENTER EXPERIENCE. (September 2021) - Pallio, S.; Santagati, A.; Sinagra, E.; D'Amore, F.; Conoscenti, G.; Romeo, F.; Borina, E.; Melita, G.; Tortora, A.; Rossi, F.; Tarantino, I.; Raimondo, D.