Perhaps you should try some spelling variations:
der filosofia » de filosofia, di filosofia, da filosofia
safe studien » aue studien, safe studio, safety studies
y literatura » la literatura
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.

• If you are trying to use Boolean operators, they must be ALL CAPS: tests safe studien ((der filosofia) OR (e filosofia)) y literatura.
• Adding a wildcard symbol may retrieve word variants: tests safe studien ((der filosofia) or (e filosofia)) y literatura*.