Perhaps you should try some spelling variations:
population pressures » population pressure, population censuses, population census
integration efforts » international efforts, conservation efforts
school population » school education, poor population, school completion
chain integration » trade integration, data integration, grid integration
survey school » nursery school, supply school

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

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