Perhaps you should try some spelling variations:
e filosofico » e filosofica, y filosofico, e filosofiche
a literatura » la literatura, a literature, a literatur
y literatura » la literatura
4 studies » 2 studies
1 studie » 1 studies, 1 studien, 3 studie

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: test ((1 studie) OR (4 studies)) e filosofico ((a literatura) OR (y literatura)).
• The words AND, OR and NOT may confuse the search; try adding quotes: "test ((1 studie) or (4 studies)) e filosofico ((a literatura) OR (y literatura))".
• Adding a wildcard symbol may retrieve word variants: test ((1 studie) or (4 studies)) e filosofico ((a literatura) OR (y literatura))*.