Perhaps you should try some spelling variations:
passiv » passive, passiven, passiver
passivieren » passiveieren, passivenieren, passiverieren, passivierende, passivierung, passieren
passiverwerb » passiveerwerb, passivenerwerb, passivererwerb, passiverer
massiv » massive

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 massiv) OR passivieren) OR (passiverwerb OR passiert))*.
• The words AND, OR and NOT may confuse the search; try adding quotes: "(((passiv OR massiv) or passivieren) or (passiverwerb or passiert))*".