Perhaps you should try some spelling variations:
de literatura » de litterature, la literatura, y literatura
filosofia de » filosofia del
test scale » tests scale, best scale, rest scale
study dd » study d, study de, study die
study d3 » study d, study de, study die

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 scale ((study dd) OR (study d3)) filosofia de literatura".
• Adding a wildcard symbol may retrieve word variants: test scale ((study dd) OR (study d3)) filosofia de literatura*.