Try imslp.org
Its free and has pretty much every piece of music you can think of! You can look for quartet pieces too in there.
Typically a string quartet is two violins, one viola, one cello.
The classical string quartet has a first and second violin, a viola and a cello. It was formalized by Franz Josef Haydn and perfected by him and Mozart. Nearly every classical composer since their time has written at least one string quartet.
the difference between cello and viola music is that cello sounds lower then viola
A standard string quartet is made of two violins, a viola, and a cello. The cello is the lowest.
Two violins, a viola, and a cello.
Violin, Viola ,Cello and Bass
1st violin 2nd violin Viola Cello
Typically a string quartet is two violins, one viola, one cello.
A string quartet
Two violins, viola, and cello
First violin, second violin, viola, cello.
Usually, two violins, a viola, and a cello.