Perhaps you should try some spelling variations:
income distributions » income distribution, income redistribution, time distributions
2f developing » 2.3 developing, 2.2 developing, 2.1 developing
f developing » self developing, turf developing, 2.1 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 distributions) OR (stable distributions)) %((2f developing) OR (f developing)) countries%22.
• The words AND, OR and NOT may confuse the search; try adding quotes: "%((income distributions) or (stable distributions)) %((2f developing) OR (f developing)) countries%22".
• Adding a wildcard symbol may retrieve word variants: %((income distributions) or (stable distributions)) %((2f developing) OR (f developing)) countries%22*.