Perhaps you should try some spelling variations:
population pressures » population pressure, population censuses, population census
integration efforts » international efforts, conservation efforts
poor population » world population
supply trade » supply side, supply case
survey poor » survey labor

You may be able to get more results by adjusting your search query.

• Performing a fuzzy search may retrieve terms with similar spellings: (( survey poor population pressures. ) or ( supply trade integration efforts. ))~.
• If you are trying to use Boolean operators, they must be ALL CAPS: (( survey poor population pressures. ) OR ( supply trade integration efforts. )).
• Adding a wildcard symbol may retrieve word variants: (( survey poor population pressures. ) or ( supply trade integration efforts. ))*.