A Student's Song of Heidelberg (German:Ein Burschenlied aus Heidelberg) is a 1930 German musical film directed by Karl Hartl and starring Hans Brausewetter, Betty Bird and Willi Forst. It marked Hartl's directoral debut. The film is in the tradition of the nostalgic Old Heidelberg.

Based on the paragraph above can we conclude that "Hartl never directed another film after A Student's Song of Heidelberg. "?
It's impossible to say