Perhaps you should try some spelling variations:
22income distribution » income distributions, income redistribution, genome distribution
future developing » future development, future developments, care developing
turf developing » stuff developing, tariff developing, turkey 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: %((((22income distribution) OR (income distribution))) OR (discrete distributions)) %((turf developing) OR (future developing)) countries%22.
• Adding a wildcard symbol may retrieve word variants: %((((22income distribution) or (income distribution))) or (discrete distributions)) %((turf developing) or (future developing)) countries%22*.