Perhaps you should try some spelling variations:
delle studien » duale studien, delphi studien, modell studien
der filosofia » de filosofia, di filosofia, da filosofia
y literatura » la literatura
e filosofia » la filosofia
test delle » testi delle, tesi delle, test della

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 delle studien ((der filosofia) OR (e filosofia)) y literatura".
• Adding a wildcard symbol may retrieve word variants: test delle studien ((der filosofia) OR (e filosofia)) y literatura*.