Perhaps you should try some spelling variations:
duale studium » duales studium, dualen studium
ds filosofica » di filosofia, da filosofia, e filosofica
de filosofia » e filosofia, di filosofia, la filosofia
a literatura » la literatura, a literature, y literatura

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 ((duale studium) OR (das studium)) ((ds filosofica) OR (de filosofia)) a literatura.
• The words AND, OR and NOT may confuse the search; try adding quotes: "test ((duale studium) OR (das studium)) ((ds filosofica) or (de filosofia)) a literatura".
• Adding a wildcard symbol may retrieve word variants: test ((duale studium) OR (das studium)) ((ds filosofica) or (de filosofia)) a literatura*.