Perhaps you should try some spelling variations:
income distributions » time distributions, discrete distributions, size distributions
self developing » relief developing, self development, level developing
70 developing » 10 developing, 20 developing, 30 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 redistribution) OR (((income distributions) OR (income distribution)))) %((self developing) OR (70 developing)) countries%22.
• Adding a wildcard symbol may retrieve word variants: %((income redistribution) or (((income distributions) or (income distribution)))) %((self developing) or (70 developing)) countries%22*.