How many movies have Jörg Nagel and Wolf C. Hartwig collaborated on?

They have worked on 3 movies together! Their first movie together was Sex in the Office (1971) while their highest rated movie together was Schoolgirl Report Part 2: What Keeps Parents Awake at Night (1971). They have not worked together since Schoolgirl Report Part 8: What Parents Must Never Know (1974). They are most known for their drama films together.