Perhaps you should try some spelling variations:
mittelbar » mittelbare, unmittelbar, ermittelbar
mittelbarau » mittelbareau, unmittelbarau, ermittelbarau, mittelbare, mittelbaren, mittelbarer
mittelbis » mittelbaus, mittelbau
mittelbauar » mittelbarer, mittelbau, mittelbaus

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 mittelbis) OR mittelbauar) OR mittelbarau).
• Adding a wildcard symbol may retrieve word variants: (((mittelbar or mittelbis) or mittelbauar) or mittelbarau)*.