Perhaps you should try some spelling variations:
income distributions » income redistribution, time distributions, size distributions
2f developing » 2.3 developing, 2.2 developing, 2.1 developing
70 developing » 10 developing, 20 developing, 30 developing
f developing » self developing, turf developing, 2.1 developing

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) OR (discrete distributions)))) %((((2f developing) OR (70 developing))) OR (f developing)) countries%22.
• The words AND, OR and NOT may confuse the search; try adding quotes: "%((income distribution) or (((income distributions) or (discrete distributions)))) %((((2f developing) OR (70 developing))) or (f developing)) countries%22".
• Adding a wildcard symbol may retrieve word variants: %((income distribution) or (((income distributions) or (discrete distributions)))) %((((2f developing) OR (70 developing))) or (f developing)) countries%22*.