Perhaps you should try some spelling variations:
massiv » massive
passiver » passive, passiven, passively
aktivierende » motivierende, praktizierende, motivierenden
aktivierenden » motivierenden, praktizierenden, motivierendenn, motivierende
aktivieren » 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 (aktivieren OR aktivierung)) OR aktivierenden)).
• The words AND, OR and NOT may confuse the search; try adding quotes: "((massiv or passiver) or ((aktivierende or (aktivieren OR aktivierung)) or aktivierenden))".
• Adding a wildcard symbol may retrieve word variants: ((massiv or passiver) or ((aktivierende or (aktivieren OR aktivierung)) or aktivierenden))*.