Perhaps you should try some spelling variations:
learning inequality » earnings inequality, measuring inequality, deepening inequality
garding inequality » garding's inequality, earnings inequality, hardy's inequality
hardy inequality » hardy's inequality, hardy inequalities, harnack inequality
learning quality » learning ability
wage » wave

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: wage AND ((((((learning inequality) OR (((garding inequality) OR (hardy inequality))))) OR (measuring quality))) OR (learning quality)).
• Adding a wildcard symbol may retrieve word variants: wage and ((((((learning inequality) or (((garding inequality) or (hardy inequality))))) or (measuring quality))) or (learning quality))*.