Perhaps you should try some spelling variations:
passiv » massiv, passiven
passive » massive, passivene
passiverer » massiverer, passivenerer, passiverwerb, passivieren, passieren, passivener, passivelyer, passierter
passiver » massiver, passivener, passiven, passively, passiert

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 passive) OR (passiverer OR passiver)).
• Adding a wildcard symbol may retrieve word variants: ((passiv or passive) or (passiverer or passiver))*.