Perhaps you should try some spelling variations:
income distributions » income redistribution, time distributions, size distributions
2self developing » gisela developing, yourself developing, relief developing
self developing » relief developing, self development, level developing

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• If you are trying to use Boolean operators, they must be ALL CAPS: %((income distribution) OR (((income distributions) OR (discrete distributions)))) %((2self developing) OR (self developing)) countries%22.
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