Perhaps you should try some spelling variations:
22income distribution » income redistribution, genome distribution, income distributional
income distributions » income redistribution, time distributions, discrete distributions
size distributions » size distribution
2f developing » f developing, self developing, turf 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: %((((22income distribution) OR (income distribution))) OR (((income distributions) OR (size distributions)))) %2f developing countries%22.
• Adding a wildcard symbol may retrieve word variants: %((((22income distribution) or (income distribution))) or (((income distributions) or (size distributions)))) %2f developing countries%22*.