Heinrich Ernest Kayser (1815-1888), born in Germany, was a violinist, violist, pedagogue and composer.
What you are studying now, 36 Etudets, elementary and progressive etudes for violin op.20, by Kayser is one of the most important etude books for violinists.
These etudes are a must for any serious students of the violin.
He lived about the same time as Dont, Schumann, and Wagner in Germany, as well as Liszt (Hungary), Verdi(Italy), Vieuxtemps(Belgium), Gounod(France), and Foster(America).
Kayser can be considered a composer in Romantic era.