Perhaps you should try some spelling variations:
population pressures » population pressure, population research
labor population » larger population, labor regulation, poor population
aid conservation » land conservation, bird conservation, wild conservation
survey labor » survey aon, survey error
supply aid » supply asia, supply a, supply ann

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

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