Perhaps you should try some spelling variations:
22income distribution » income distribution, income redistribution, genome distribution
income distributions » income distribution, income redistribution, discrete distributions
time distributions » time distribution, size distributions, stable distributions
30 development » 10 development, 20 development, 10 developments
2f developing » f developing, self developing, turf developing
70 developing » 10 developing, 30 developing, 40 developing
20 developing » 10 developing, 20 development

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 distributions) OR (time distributions)))) %((2f developing) OR (((((70 developing) OR (30 development))) OR (20 developing)))) countries%22.
• The words AND, OR and NOT may confuse the search; try adding quotes: "%((22income distribution) or (((income distributions) OR (time distributions)))) %((2f developing) or (((((70 developing) or (30 development))) or (20 developing)))) countries%22".
• Adding a wildcard symbol may retrieve word variants: %((22income distribution) or (((income distributions) OR (time distributions)))) %((2f developing) or (((((70 developing) or (30 development))) or (20 developing)))) countries%22*.