Perhaps you should try some spelling variations:
massivieren » passivieren, massivere, massigeren
passivierung » aktivierung
massiveren » massivere, massigeren, massivement
massiveeren » massivere, passivieren, massigeren

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: (((passiven OR passion) OR passive) OR ((massivieren OR passivierung) OR (massiveren OR massiveeren))).
• The words AND, OR and NOT may confuse the search; try adding quotes: "(((passiven OR passion) or passive) or ((massivieren or passivierung) or (massiveren or massiveeren)))".
• Adding a wildcard symbol may retrieve word variants: (((passiven OR passion) or passive) or ((massivieren or passivierung) or (massiveren or massiveeren)))*.