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