Perhaps you should try some spelling variations:
mittelbar » mittelbare, ermittelbar, unmittelbare
unmittelbar » unmittelbare, unermittelbar, ununmittelbare
unerermittelbar » unerermittelbare, unererermittelbar, unererunmittelbare, unvermittelbar, unvermittelbare
unererunmittelbare » unererunmittelbaree, unererunermittelbare, unererununmittelbaree, fuhrerunmittelbare, bundesunmittelbare, unvermittelbare
unmittelbaren » unmittelbareen, unermittelbaren, ununmittelbareen, unmittelbare
mittelbisau » mittelbau, mittelbis

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