Perhaps you should try some spelling variations:
mittelbare » unmittelbare, unmittelbaren, ermittelbare, unmittelbaree
ununmittelbaren » unununmittelbaren, unununmittelbarenn, ununermittelbaren, unununmittelbareen, unmittelbaren, unmittelbare, unmittelbarer
mittelbar » ermittelbar, unmittelbare
unmittelbar » unermittelbar, ununmittelbare

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: ((((mittelbau OR mittelbach) OR mittelbare) OR (mittelbar OR unmittelbar)) OR ununmittelbaren).
• The words AND, OR and NOT may confuse the search; try adding quotes: "((((mittelbau OR mittelbach) or mittelbare) or (mittelbar or unmittelbar)) or ununmittelbaren)".
• Adding a wildcard symbol may retrieve word variants: ((((mittelbau OR mittelbach) or mittelbare) or (mittelbar or unmittelbar)) or ununmittelbaren)*.