Perhaps you should try some spelling variations:
mittelbar » unmittelbar, unmittelbare
mittelbare » unmittelbare, unmittelbaree
unmittelbaren » ununmittelbaren, ununmittelbareen, unmittelbare, unmittelbar
ermittelbar » erunmittelbar, erunmittelbare, unmittelbar

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