Perhaps you should try some spelling variations:
stufe studien » studie studien, stufen studie, studien studien
filosofia da » filosofia de, filosofia del, filosofia della
erste stufe » erster stufe
filosofia e » filosofia de, filosofia del
studien e » studien es, studien _, studien 3

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: "erste stufe studien e ((filosofia da) OR (filosofia e)) literatura".
• Adding a wildcard symbol may retrieve word variants: erste stufe studien e ((filosofia da) OR (filosofia e)) literatura*.