Perhaps you should try some spelling variations:
22income distribution » income distribution, income distributions, income redistribution
time distributions » time distribution, size distributions, stable distributions
2.3 developing » 23 developing, 3.3 developing, 4.3 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 (time distributions)) %2.3 developing countries%22.
• Adding a wildcard symbol may retrieve word variants: %((22income distribution) or (time distributions)) %2.3 developing countries%22*.