Perhaps you should try some spelling variations:
"supply national immigration policies." » "supply national integration policies.", "supply national irrigation policies.", "supply national immunization policies.", "supply national immigration policy.", "supply national migration policy."
"supply grid integration theory." » "supply grid integration through.", "supply grid information theory.", "supply grid integration report.", "supply trade integration theory.", "supply _ integration theory.", "supply data integration theory.", "supply crowd integration theory.", "support grid integration theory."

Try widening your search to All Fields.

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• Performing a fuzzy search may retrieve terms with similar spellings: (("supply national immigration policies.") or ("supply grid integration theory."))~.
• If you are trying to use Boolean operators, they must be ALL CAPS: (("supply national immigration policies.") OR ("supply grid integration theory.")).
• Removing quotes may allow a broader search: (( supply national immigration policies. ) or ( supply grid integration theory. )).
• Adding a wildcard symbol may retrieve word variants: (("supply national immigration policies.") or ("supply grid integration theory."))*.