Perhaps you should try some spelling variations:
"supply through immigration policies." » "supply through immigration policy.", "supply through migration policy.", "supply through integration policies.", "supply through irrigation policies.", "support through immigration policies."
"supply tool integration theories." » "supply tool integration theory.", "supply tool integration through.", "supply tool integration efforts.", "supply global integration theories.", "supply social integration theories.", "supply trade integration theories.", "supply school integration theories.", "support tool integration theories."

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

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