Perhaps you should try some spelling variations:
"supply chain immigration policies." » "supply chain immigration policy.", "supply chain migration policy.", "supply chain migration policies.", "supply chain integration policies.", "supply chinese immigration policies."
"supply grid integration theories." » "supply grid integration theorems.", "supply grid integrationstheorie 2.", "supply grid integration theory.", "supply crowd integration theories.", "supply great integration theories.", "support grid integration theories."

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

• The words AND, OR and NOT may confuse the search; try adding quotes: "((\"supply chain immigration policies.\") OR (\"supply grid integration theories.\"))~".
• Removing quotes may allow a broader search: (( supply chain immigration policies. ) OR ( supply grid integration theories. ))~.
• Adding a wildcard symbol may retrieve word variants: (("supply chain immigration policies.") OR ("supply grid integration theories."))*.