Perhaps you should try some spelling variations:
della studien » cella studie, delphi studien, modell studien
le literatura » la literatura, de literatura, de litteratura
e literatura » de literatura, y literatura, e literatur
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 (e literatura))*".