Check out how Dvorak used African American spirituals in a composition he wrote while on vacation in Iowa, and how “General” Beethoven helped break down the containment of the classical era with his creative innovation.
String Quartet No. 12 in F, Op. 96, B. 179, "American" Antonin Dvorak
String Quartet No. 11 in F minor, Op. 95, "Serioso" Ludwig van Beethoven