Spartiti musicali - Music scores
Musescore.com duetti vocali
Www.free-scores
IMSLP - Petrucci Music Library
Swiss-jazz.ch/free-scores-1.htm
You've got a friend (chitarra e voce)
https://www.youtube.com/watch?v=9SxToTUoWGM&feature=em-subs_digest-vrecs
Musescore.com