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