Perhaps you should try some spelling variations:
mittelbar » mittelbare, unmittelbar, unmittelbare
ermittelbar » ermittelbare, erunmittelbar, erunmittelbare, unmittelbar
erunmittelbare » erunmittelbaree, erununmittelbare, erununmittelbaree, unmittelbare, ermittelbare, unmittelbar
mittelbisau » mittelbau, mittelbis

You may be able to get more results by adjusting your search query.

• If you are trying to use Boolean operators, they must be ALL CAPS: ((mittelbar OR (ermittelbar OR erunmittelbare)) OR mittelbisau)*.
• The words AND, OR and NOT may confuse the search; try adding quotes: "((mittelbar or (ermittelbar OR erunmittelbare)) or mittelbisau)*".