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

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