Perhaps you should try some spelling variations:
income distributions » income redistribution, discrete distributions, stable distributions
time distributions » time distribution, stable distributions, time distributed
size distributions » size distribution
2f developing » f developing, 2.3 developing, 2.2 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 distribution) OR (income distributions))) OR (((time distributions) OR (size distributions)))) %2f developing countries%22.
• The words AND, OR and NOT may confuse the search; try adding quotes: "%((((income distribution) or (income distributions))) or (((time distributions) OR (size distributions)))) %2f developing countries%22".
• Adding a wildcard symbol may retrieve word variants: %((((income distribution) or (income distributions))) or (((time distributions) OR (size distributions)))) %2f developing countries%22*.