Yesterday I have discovered the website of the CHASE project.
Collection of Historical Annotated String Editions
19th- and Early 20th-Century Annotated Editions of String Music:
Bibliographical Problems, Editorial Content and Implications for Performance Practice
This website is a great resource about the violin and other stringed instruments. You can find many detailed articles about the development of the instrumental technique for those instruments based on annotated editions of string music. If you are interested in the history of the violin or cello playing techniques and the way those instruments were taught, and also how the music has been played by some of the greatest violin players you should check the articles on this site.
You can find a big collection of scans of editions of violin music from the 19th and early 20th century including works by Bach, Beethoven, Mozart and many other composers. This includes also some violin methods and collections of studies.
List of works on the CHASE website – most of those works are available for free download: http://chase.leeds.ac.uk/browse/work/
One of the works that I have found is the Chaconne by Vitali
Here is a great performance of this piece by Sarah Chang:
Vitali Chaconne – Sarah Chang
Another interesting composer is Emanuele Barbella who is known as a composer for some pieces for the mandolin. You can find two pieces by Barbella: Violin Sonata in E flat major and Tinna nonna (Lullaby)
Most of the pieces available on this site will probably be found also on the IMSLP site, but maybe the selection serves as a better way to find some interesting compositions.