Perhaps you should try some spelling variations:
passiv » passive, massiv, passiven
passivieren » passiveieren, massivieren, passivenieren, passivierende, passivierung, passagieren
passiverwerb » passiveerwerb, massiverwerb, passivenerwerb, passiverer
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 passivieren) OR (passiverwerb OR passieren))*.