Perhaps you should try some spelling variations:
del litterature » de litterature, des litteratures, et litterature
test failure » test failures, post failure, fast failure
studies dan » studies dn, studies dance, studies drawn
studies das » studies ds, studie das, studien das

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 failure ((studies dan) OR (studies das)) filosofia del litterature".
• Adding a wildcard symbol may retrieve word variants: test failure ((studies dan) OR (studies das)) filosofia del litterature*.