Perhaps you should try some spelling variations:
income distributions » income redistribution, time distributions, discrete distributions
2f developing » f developing, 7 developing, self developing
70 developing » 10 developing, 20 developing, 30 developing

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• If you are trying to use Boolean operators, they must be ALL CAPS: %((income distributions) OR (income distribution)) %((2f developing) OR (70 developing)) countries%22.
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