Perhaps you should try some spelling variations:
pela literatura » la literatura, a literatura, de literatura
pena literatura » na literatura, lengua literatura, la literatura
di filosofia » la filosofia, e filosofia
tests scale » tests stable, sets scale, tests safe
study di » study die, study d, study d3

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 scale study di filosofia ((pela literatura) OR (pena literatura))*".