Perhaps you should try some spelling variations:
mittelbar » unmittelbar, ermittelbar, unmittelbare
mittelbare » unmittelbare, ermittelbare, unmittelbaree, unmittelbaren
mittelbararau » unmittelbararau, ermittelbararau, unmittelbarearau, mittelbarer
mittelbau » mittelbach

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 mittelbare) OR mittelbau) OR mittelbararau).
• The words AND, OR and NOT may confuse the search; try adding quotes: "(((mittelbar OR mittelbare) or mittelbau) or mittelbararau)".
• Adding a wildcard symbol may retrieve word variants: (((mittelbar OR mittelbare) or mittelbau) or mittelbararau)*.