Perhaps you should try some spelling variations:
le literatura » de literatura, e literatura, de litteratura
duale studien » duale studium, scale studien, duales studium
la literatura » la litterature, a literature
ds filosofia » de filosofia, da filosofia, la filosofia
di filosofia » la filosofia, e filosofia
test duale » test double, test delle, test orale

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