Perhaps you should try some spelling variations:
mittelbau » mittelbare, mittelbach
mittelbar » mittelbare, ermittelbar
unmittelbaren » unmittelbareen, unermittelbaren, ermittelbarn
unmittelbare » unmittelbaree, unermittelbare, ermittelbar
unmittelbar » unmittelbare, unermittelbar

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: ((mittelbau OR (mittelbar OR (unmittelbaren OR unmittelbare))) OR unmittelbar).
• Adding a wildcard symbol may retrieve word variants: ((mittelbau or (mittelbar or (unmittelbaren or unmittelbare))) or unmittelbar)*.