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