Perhaps you should try some spelling variations:
mittelbar » mittelbare, unmittelbare
ermittelbar » ermittelbare, erunmittelbare
erunmittelbare » erunmittelbaree, erununmittelbaree, unmittelbare, ermittelbare, unmittelbaren
unmittelbar » unmittelbare, ununmittelbare
mittelbisau » mittelbis
mittelbau » mittelbare, 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 ((ermittelbar OR erunmittelbare) OR unmittelbar)) OR (mittelbisau OR mittelbau))*.
• The words AND, OR and NOT may confuse the search; try adding quotes: "((mittelbar or ((ermittelbar OR erunmittelbare) or unmittelbar)) or (mittelbisau or mittelbau))*".