Perhaps you should try some spelling variations:
del literatura » de literatura, pela literatura, da literatura
orale studien » frage studien, scale studien, globale studien
duale studien » duale studium, scale studien, duales studium
ds filosofia » di filosofia, de filosofia, da filosofia

You may be able to get more results by adjusting your search query.

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