Perhaps you should try some spelling variations:
"mittelbar" » "mittelbare", "ermittelbar", "unmittelbare"
"unmittelbar" » "unmittelbare", "unermittelbar", "ununmittelbare"
"unermittelbar" » "unermittelbare", "unerermittelbar", "unerunmittelbare", "unvermittelbar", "unvermittelbare", "ermittelbar"

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 ("unmittelbar" OR "unermittelbar")).
• The words AND, OR and NOT may confuse the search; try adding quotes: "(\"mittelbar\" or (\"unmittelbar\" OR \"unermittelbar\"))".
• Removing quotes may allow a broader search: ( mittelbar or ( unmittelbar OR unermittelbar )).
• Adding a wildcard symbol may retrieve word variants: ("mittelbar" or ("unmittelbar" OR "unermittelbar"))*.