Perhaps you should try some spelling variations:
passiv » massiv, passiven, passiver
passivierender » massivierender, passivenierender, passiverierender, passivierende, aktivierender, passivieren
passive » massive, passivene, passivere
massiverwerb » passiverwerb, massivere, massierer

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 (passivierender OR massiverwerb)) OR (passive OR massive)).
• The words AND, OR and NOT may confuse the search; try adding quotes: "((passiv or (passivierender or massiverwerb)) or (passive OR massive))".
• Adding a wildcard symbol may retrieve word variants: ((passiv or (passivierender or massiverwerb)) or (passive OR massive))*.