Perhaps you should try some spelling variations:
pela literatura » pena literatura, la literatura, a literatura
die filosofia » di filosofia, de filosofia, da filosofia
safe studien » aue studien, lage studien, safe studio
e filosofia » la filosofia
tests safe » tests safety, tests scale, tests space

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: "tests safe studien ((die filosofia) OR (e filosofia)) pela literatura".
• Adding a wildcard symbol may retrieve word variants: tests safe studien ((die filosofia) OR (e filosofia)) pela literatura*.