Perhaps you should try some spelling variations:
mittelbar » mittelbare, unmittelbar
ermittelbar » ermittelbare, erunmittelbar, unmittelbar
ununmittelbare » ununmittelbaree, unununmittelbare, unvermittelbare, unmittelbar, unmittelbaren, ununmittelbar
unmittelbare » unmittelbaree, ununmittelbare, unmittelbar
mittelbis » mittelbaus, mittelbau

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 (ermittelbar OR (ununmittelbare OR unmittelbare))) OR mittelbis).
• Adding a wildcard symbol may retrieve word variants: ((mittelbar or (ermittelbar or (ununmittelbare or unmittelbare))) or mittelbis)*.