Great Violin Site with Videos - Left hand development
Carolyn Broe's article: Progressive Etudes for the Viola
David Sills' Viola Repertoire List (by category)
Colle: Collé means glued. It is a very short stroke, and begins with the bow lightly contacting the string with a distinct and short, sharp pinch. The bow is then lifted to prepare for the next stroke. The resulting sound was described by Galamian as being similar to pizzicato with the bow. Although collé usually has no articulation markings, dots are sometimes used.
THE VIOLIN LAB - Workouts for the Beginning Violinist
American String Teachers Association
Michael Hopkins String Pedagogy Notebook