Perhaps you should try some spelling variations:
income distributions » income redistribution, time distributions, discrete distributions
self developing » relief developing, self development, level developing
7.2 developing » 5.2 developing, 3.2 developing, 12 developing
f developing » 7 developing, turf developing, f development

Try widening your search to All Fields.

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 distribution) OR (income distributions)) %((((7.2 developing) OR (self developing))) OR (f developing)) countries%22.
• Adding a wildcard symbol may retrieve word variants: %((income distribution) or (income distributions)) %((((7.2 developing) or (self developing))) or (f developing)) countries%22*.