Perhaps you should try some spelling variations:
delle studien » duale studien, delphi studien, modell studien
filosofia le » filosofia e, filosofia del, filosofia da
filosofia de » filosofia del
studien der » studie der, studien die, studenten der
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 le) OR (filosofia de)) literatura".
• Adding a wildcard symbol may retrieve word variants: test delle studien der ((filosofia le) OR (filosofia de)) literatura*.