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