Perhaps you should try some spelling variations:
la literatura » la litterature, a literature
orale studien » duale studien, frage studien, scale studien
ds filosofia » di filosofia, de filosofia, la filosofia
da filosofia » la filosofia, di filosofia, a filosofia
test orale » test oracle, test oral, test oracles

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 orale studien ((ds filosofia) OR (da filosofia)) la literatura.
• Adding a wildcard symbol may retrieve word variants: test orale studien ((ds filosofia) or (da filosofia)) la literatura*.