Perhaps you should try some spelling variations:
de literatura » de litterature, la literatura, y literatura
le literatura » la literatura, e literatura, de litteratura
di filosofia » la filosofia, e filosofia
tests space » test space, texts space, lists space
tests safe » tests safety, tests scale, tests tafel
studie di » studie die, studie d, studie de

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 safe) OR (tests space)) studie di filosofia ((le literatura) OR (de literatura)).
• The words AND, OR and NOT may confuse the search; try adding quotes: "((tests safe) or (tests space)) studie di filosofia ((le literatura) OR (de literatura))".
• Adding a wildcard symbol may retrieve word variants: ((tests safe) or (tests space)) studie di filosofia ((le literatura) OR (de literatura))*.