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