Perhaps you should try some spelling variations:
passiver » passive, passiert
passively » massively, passive, passivity
passiven » passive, passion
passieren » passiert
passivierender » passivierende, aktivierender, passivieren

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: (((passiver OR passively) OR (passiven OR passieren)) OR passivierender).
• The words AND, OR and NOT may confuse the search; try adding quotes: "(((passiver OR passively) or (passiven or passieren)) or passivierender)".
• Adding a wildcard symbol may retrieve word variants: (((passiver OR passively) or (passiven or passieren)) or passivierender)*.