Perhaps you should try some spelling variations:
"supply scale irrigation countries." » "supply scale immigration countries.", "supply scale emigration countries.", "supply scale irrigation sources.", "supply case irrigation countries.", "supply scheme irrigation countries.", "supply social irrigation countries."
"supply affect migration policy." » "supply affect education policy.", "supply net migration policy.", "supply great migration policy.", "supply effect migration policy.", "supply aspect migration policy.", "supply aspects migration policy."

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

• Performing a fuzzy search may retrieve terms with similar spellings: (("supply affect migration policy.") or ("supply scale irrigation countries."))~.
• If you are trying to use Boolean operators, they must be ALL CAPS: (("supply affect migration policy.") OR ("supply scale irrigation countries.")).
• Removing quotes may allow a broader search: (( supply affect migration policy. ) or ( supply scale irrigation countries. )).
• Adding a wildcard symbol may retrieve word variants: (("supply affect migration policy.") or ("supply scale irrigation countries."))*.