Perhaps you should try some spelling variations:
passiv » passive, massiv, passiven
passiverwerb » passiveerwerb, massiverwerb, passivenerwerb, passiverer
passiveren » passiveeren, massiveren, passiveneren, passivieren, passiverer, passiven
passieren » passiert, passiven

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: ((passiv OR (passieren OR passiverwerb)) OR passiveren).
• Adding a wildcard symbol may retrieve word variants: ((passiv or (passieren or passiverwerb)) or passiveren)*.