Perhaps you should try some spelling variations:
learning inequality » earnings inequality, measuring inequality, deepening inequality
garding inequality » garding's inequality, earnings inequality, hardy inequality
hardy's inequality » hardy inequality, holder's inequality, 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's inequality))))) OR (learning quality)).
• The words AND, OR and NOT may confuse the search; try adding quotes: "wage and ((((learning inequality) or (((garding inequality) OR (hardy's inequality))))) or (learning quality))".
• Adding a wildcard symbol may retrieve word variants: wage and ((((learning inequality) or (((garding inequality) OR (hardy's inequality))))) or (learning quality))*.