Perhaps you should try some spelling variations:
mittelbar » mittelbare, unmittelbar
ermittelbar » ermittelbare, erunmittelbar, unmittelbar
unmittelbare » unmittelbaree, ununmittelbare, unmittelbar
mittelbach » mittelbare

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