Perhaps you should try some spelling variations:
learning inequality » earnings inequality, learning quality, measuring inequality
garding inequality » garding's inequality, earnings inequality, hardy inequality
warning inequality » earnings inequality, widening inequality, facing inequality
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 (young's inequality))) OR (warning inequality)))).
• Adding a wildcard symbol may retrieve word variants: wage and ((learning inequality) or (((((garding inequality) or (young's inequality))) or (warning inequality))))*.