Perhaps you should try some spelling variations:
mittelbar » mittelbare, unmittelbar, ermittelbar
unermittelbare » unermittelbaree, unerunmittelbare, unerermittelbare, unvermittelbare, unmittelbare, ermittelbare
unmittelbaren » unmittelbareen, ununmittelbaren, unermittelbaren, unmittelbare, unmittelbar
mittelbach » mittelbare

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 mittelbach) OR (unermittelbare OR unmittelbaren)).
• Adding a wildcard symbol may retrieve word variants: ((mittelbar or mittelbach) or (unermittelbare or unmittelbaren))*.