Perhaps you should try some spelling variations:
del litterature » de litterature, des litteratures, et litterature
files studies » films studies, fishes studies, film studies
da filosofia » di filosofia, a filosofia, de filosofia
test files » text files, test file

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 files studies ((da filosofia) OR (la filosofia)) del litterature".
• Adding a wildcard symbol may retrieve word variants: test files studies ((da filosofia) OR (la filosofia)) del litterature*.