Perhaps you should try some spelling variations:
passiv » passive, massiv, passiven
passiverer » passiveerer, massiverer, passivenerer, passiverwerb, passivieren, passiver
massivere » massiver, massive, massiven
massively » massive
aktivierenden » aktivieren, motivierende

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 (passiverer OR (massivere OR massively))) OR aktivierenden).
• The words AND, OR and NOT may confuse the search; try adding quotes: "((passiv or (passiverer or (massivere OR massively))) or aktivierenden)".
• Adding a wildcard symbol may retrieve word variants: ((passiv or (passiverer or (massivere OR massively))) or aktivierenden)*.