Perhaps you should try some spelling variations:
della literatura » della letteratura, pela literatura, nella letteratura
filosofia della » filosofia del, filosofia de
drugs studies » drug studies
di filosofia » la filosofia, e filosofia
drug studie » drug studies, drugs studied, drug study

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) OR (drugs studies)) di filosofia della literatura".
• Adding a wildcard symbol may retrieve word variants: tests ((drug studie) OR (drugs studies)) di filosofia della literatura*.