Perhaps you should try some spelling variations:
del literatura » de literatura, pela literatura, e literatura
des filosofia » de filosofia, e filosofia, di filosofia
da literatura » la literatura, a literatura, de literatura
drug studie » drug studies, drugs studies, drugs studied
tests drug » test drug, testing drug, tests during
studie des » studie der, studium des, studie 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: "tests drug studie des filosofia ((del literatura) OR (da literatura))".
• Adding a wildcard symbol may retrieve word variants: tests drug studie des filosofia ((del literatura) OR (da literatura))*.