Perhaps you should try some spelling variations:
mittelbar » mittelbare, unmittelbar, ermittelbar
unmittelbaree » unmittelbareee, ununmittelbaree, unermittelbaree, unmittelbare, unmittelbaren, unmittelbarer
vermittelbar » vermittelbare, verunmittelbar, verermittelbar, 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 unmittelbaree) OR ((unmittelbaree OR vermittelbar) OR unmittelbaree)).
• Adding a wildcard symbol may retrieve word variants: ((mittelbar or unmittelbaree) or ((unmittelbaree or vermittelbar) or unmittelbaree))*.