Perhaps you should try some spelling variations:
"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."
"support grid irrigation systems." » "support drip irrigation systems.", "support syria irrigation systems.", "support crop irrigation systems.", "support agri irrigation systems.", "support grant irrigation systems.", "support group irrigation systems.", "support grid irrigation system."

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 chain integration theories.") OR ("support grid irrigation systems."))~.
• Removing quotes may allow a broader search: (( supply chain integration theories. ) or ( support grid irrigation systems. ))~.
• Adding a wildcard symbol may retrieve word variants: (("supply chain integration theories.") or ("support grid irrigation systems."))*.