Question: What nationality is the director of film Petronella (Film)?
Sentence (from "Petronella (film)"): Petronella (German: Petronella - Das Geheimnis der Berge) is a 1927 German-Swiss silent historical film directed by Hanns Schwarz and starring Maly Delschaft, William Dieterle and Oskar Homolka.
Relevant evidence: Yes