hello cathe02 .me is harmojack .having known paul chalier (known as pablo caliero) I know that it made a method, that you will find at di arezzo, only s is for chromatic bandoneon, if not there is for concertina .you can also inform you by telephoning with the conservatory of Paris, you can also see on youtube those which practises this instrument and their tel or to write to see if necessary, their mall . When the easy piece see tangos of dino margelli Here it gives me a great idea, you will phone to louis corchia he must have your happiness his father (primo corchia) was a master in bando. There are quite a lot of scores of him on the site. Voila, basically, if you dry I'll help you; good luck.