Perhaps you should try some spelling variations:
massiv » massive
passiver » passive, passiven, passively
aktivierende » motivierende, motivierenden, aktivierung, aktivierungde
aktivierenden » motivierenden, motivierendenn, aktivierungn, aktivierungden, motivierende
aktivieren » aktivierung, motivieren

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: ((massiv OR passiver) OR (((aktivierende OR praktizierende) OR aktivieren) OR aktivierenden)).
• The words AND, OR and NOT may confuse the search; try adding quotes: "((massiv or passiver) or (((aktivierende OR praktizierende) or aktivieren) or aktivierenden))".
• Adding a wildcard symbol may retrieve word variants: ((massiv or passiver) or (((aktivierende OR praktizierende) or aktivieren) or aktivierenden))*.