Perhaps you should try some spelling variations:
income redistribution » income distribution
income distributions » income distribution, time distributions, discrete distributions
self developing » relief developing, self development, level developing

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: %((income redistribution) OR (income distributions)) %self developing countries%22.
• Adding a wildcard symbol may retrieve word variants: %((income redistribution) or (income distributions)) %self developing countries%22*.