Perhaps you should try some spelling variations:
duale studien » duale studium, scale studien, duales studium
filosofica da » filosofia de, filosofia di, filosofica e
filosofia da » filosofia de, filosofia del, filosofia e
tests duale » tests due, tests scale, tests damage
studien die » studie die, studien der

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: tests duale studien die ((filosofica da) OR (filosofia da)) literatura.
• Adding a wildcard symbol may retrieve word variants: tests duale studien die ((filosofica da) or (filosofia da)) literatura*.