Perhaps you should try some spelling variations:
"Supply chain immigration policies." » "Supply chain immigration policy.", "Supply chain migration policy.", "Supply mass immigration policies.", "Supply anti immigration policies.", "Supply change migration policies."
"supply chain integration theories." » "supply chain integration theory.", "supply chain integration through.", "supply chain integration efforts.", "supply trade integration theories.", "supply data integration theories.", "supply grid 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 chain immigration policies.") or ("supply chain integration theories."))~.
• If you are trying to use Boolean operators, they must be ALL CAPS: (("Supply chain immigration policies.") OR ("supply chain integration theories.")).
• Removing quotes may allow a broader search: (( Supply chain immigration policies. ) or ( supply chain integration theories. )).
• Adding a wildcard symbol may retrieve word variants: (("Supply chain immigration policies.") or ("supply chain integration theories."))*.