Perhaps you should try some spelling variations:
filosofia da » filosofia de, filosofia del, filosofia e
filosofia a » filosofia la, filosofia e, filosofia _
studie der » studium der
studie de » studie die, studie des, studies de
tests » test, texts

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 mit ((studie de) OR (studie der)) ((filosofia a) OR (filosofia da)) literature.
• The words AND, OR and NOT may confuse the search; try adding quotes: "tests mit ((studie de) or (studie der)) ((filosofia a) OR (filosofia da)) literature".
• Adding a wildcard symbol may retrieve word variants: tests mit ((studie de) or (studie der)) ((filosofia a) OR (filosofia da)) literature*.