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