Perhaps you should try some spelling variations:
dualen studium » duales studium, duale studium
test dualen » des dualen, test doubles
studium das » studium des, studium der, studium die
filosofia a » filosofia da, filosofia la, filosofia _
filosofia e » filosofia de, filosofia del

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: test dualen studium das ((filosofia a) OR (filosofia e)) literatura*.