How many movies have Heinrich Gretler and Robert Blum collaborated on?

They have worked on 12 movies together! Their first movie together was Wie d'Warret würkt (1933) while their highest rated movie together was Heidi (1952). They have not worked together since Anne Bäbi Jowager, Part 2 - Jakobli and Meyeli (1961). They are most known for their drama films together.