Perhaps you should try some spelling variations:
tests example » tests examples, test example, test examples
studies does » studies dress, studies ds, studies do
filosofica a » filosofica da, filosofica e, filosofica _
a literatura » la literatura, a literature, y literatura
studies der » studies ds, studies d, studies dn

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 example ((studies der) OR (studies does)) filosofica a literatura.
• Adding a wildcard symbol may retrieve word variants: tests example ((studies der) or (studies does)) filosofica a literatura*.