Composers of classical music have often made use of <answer>folk</answer> music (music created by musicians who are commonly not classically trained, often from a purely oral tradition). Some composers, like Dvořák and Smetana, have used <answer>folk</answer> themes to impart a nationalist flavor to their work, while others like Bartók have used specific themes lifted whole from their <answer>folk</answer>-music origins.
Dovrak has used what type of themes to impart a nationalist flavor?
folk