Perhaps you should try some spelling variations:
della studien » cella studie, delphi studien, modell studien
le literatura » la literatura, e literatura, de litteratura
de literatura » de litterature, la literatura, y literatura
testi della » test della, testa della, testi delle

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 _ filosofia ((le literatura) OR (de literatura))".
• Adding a wildcard symbol may retrieve word variants: testi della studien _ filosofia ((le literatura) OR (de literatura))*.