Perhaps you should try some spelling variations:
filosoficos de » filosoficos del, filosoficas de, filosofico de
filosoficos e » filosofico e, filosoficos del, filosoficas de
die studie » eine studie
test die » test de, west die, test drive
studie y » studie 2, studie _, studie 1

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 die studie y ((filosoficos e) OR (filosoficos de)) literatura".
• Adding a wildcard symbol may retrieve word variants: test die studie y ((filosoficos e) OR (filosoficos de)) literatura*.