Perhaps you should try some spelling variations:
mittelbar » unmittelbar, ermittelbar, unmittelbare
mittelbare » unmittelbare, ermittelbare, unmittelbaree, unmittelbaren
unermittelbare » unerunmittelbare, unerermittelbare, unerunmittelbaree, unerunmittelbaren, unvermittelbare, unmittelbare, ermittelbare
vermittelbar » verunmittelbar, verermittelbar, verunmittelbare, ermittelbar, vermittelter, vermittelnder

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