Perhaps you should try some spelling variations:
la literatura » la litterature, a literature
della studien » cella studie, delphi studien, modell studien
di filosofia » la filosofia, e filosofia
testi della » test della, testa della, testi delle
a filosofia » la filosofia, e 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: "testi della studien ((a filosofia) OR (di filosofia)) la literatura".
• Adding a wildcard symbol may retrieve word variants: testi della studien ((a filosofia) OR (di filosofia)) la literatura*.