Perhaps you should try some spelling variations:
mittelbau » mittelbare, mittelbach
mittelbar » mittelbare, unmittelbar, ermittelbar
unermittelbare » unermittelbaree, unerunmittelbare, unerermittelbare, unvermittelbare, unmittelbare, ermittelbare
mittelbisau » 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: ((mittelbau OR (mittelbar OR unermittelbare)) OR mittelbisau).
• Adding a wildcard symbol may retrieve word variants: ((mittelbau or (mittelbar or unermittelbare)) or mittelbisau)*.