Perhaps you should try some spelling variations:
del literatura » de literatura, pela literatura, da literatura
studies die » studie die, studien die, studies does
studies di » studies div, studies ds, studies d
test drug » tests drug, best drugs, test du

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 drug ((studies di) OR (studies die)) filosofia del literatura".
• Adding a wildcard symbol may retrieve word variants: test drug ((studies di) OR (studies die)) filosofia del literatura*.