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, 2.1 developing, self 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.
• The words AND, OR and NOT may confuse the search; try adding quotes: "%((((((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*.