Perhaps you should try some spelling variations:
"supply can integration theories." » "supply can integration theory.", "supply can integration through.", "supply can integration efforts.", "supply chain integration theories.", "supply care integration theories.", "supply urban integration theories.", "supply case integration theories.", "supply a integration theories."
"supply china immigration policy." » "supply china migration policy.", "supply china integration policy.", "supply child migration policy.", "supply national immigration policy.", "supply chains immigration policy.", "supply chain immigration policy."

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

• If you are trying to use Boolean operators, they must be ALL CAPS: (("supply china immigration policy.") OR ("supply can integration theories."))~.
• Removing quotes may allow a broader search: (( supply china immigration policy. ) or ( supply can integration theories. ))~.
• Adding a wildcard symbol may retrieve word variants: (("supply china immigration policy.") or ("supply can integration theories."))*.