Perhaps you should try some spelling variations:
mittelbar » unmittelbar, ermittelbar
unmittelbare » ununmittelbare, unermittelbare, unmittelbar
ununmittelbare » unununmittelbare, ununermittelbare, ununmittelbar, unvermittelbare, unmittelbar, unmittelbarer
mittelbare » unmittelbare, ermittelbare
unmittelbaren » ununmittelbaren, unermittelbaren, unmittelbarn, 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: ((mittelbach OR ((mittelbar OR ((unmittelbare OR ununmittelbare) OR ununmittelbare)) OR mittelbare)) OR unmittelbaren).
• The words AND, OR and NOT may confuse the search; try adding quotes: "((mittelbach or ((mittelbar or ((unmittelbare OR ununmittelbare) or ununmittelbare)) or mittelbare)) or unmittelbaren)".
• Adding a wildcard symbol may retrieve word variants: ((mittelbach or ((mittelbar or ((unmittelbare OR ununmittelbare) or ununmittelbare)) or mittelbare)) or unmittelbaren)*.