Perhaps you should try some spelling variations:
"supply trade integration theories." » "supply trade integration theorems.", "supply trade integrationstheorie 2.", "supply trade integration theory.", "supply case integration theories."
"supply channels irrigation schemes." » "supply change irrigation schemes.", "supply canal irrigation schemes.", "supply channels information schemes.", "supply channels irrigation scheme.", "supply channels irrigation systems.", "supply chains irrigation schemes."

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 trade integration theories.") OR ("supply channels irrigation schemes."))~.
• Removing quotes may allow a broader search: (( supply trade integration theories. ) or ( supply channels irrigation schemes. ))~.
• Adding a wildcard symbol may retrieve word variants: (("supply trade integration theories.") or ("supply channels irrigation schemes."))*.