Perhaps you should try some spelling variations:
passiv » passive, massiv, passiven
passiverer » passiveerer, massiverer, passivenerer, passiverwerb, passivieren, passiver
passiveneren » passiveeneren, massiveneren, passiveneneren, passivieren
passieren » 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 passiert) OR passiverer) OR passiveneren)).
• The words AND, OR and NOT may confuse the search; try adding quotes: "(passiv or (((passieren OR passiert) or passiverer) or passiveneren))".
• Adding a wildcard symbol may retrieve word variants: (passiv or (((passieren OR passiert) or passiverer) or passiveneren))*.