Perhaps you should try some spelling variations:
"support trade integration theories." » "support trade integration theorems.", "support trade integrationstheorie 2.", "support trade integration theory.", "support trainer integration theories.", "export trade integration theories.", "import trade integration theories."
"supply grid irrigation scheme." » "supply grid irrigation systems.", "supply grain irrigation scheme.", "supply drip irrigation scheme.", "supply gray irrigation scheme.", "supply crowd irrigation scheme.", "supply great irrigation scheme.", "support grid irrigation scheme."

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

• Performing a fuzzy search may retrieve terms with similar spellings: (("support trade integration theories.") or ("supply grid irrigation scheme."))~.
• If you are trying to use Boolean operators, they must be ALL CAPS: (("support trade integration theories.") OR ("supply grid irrigation scheme.")).
• Removing quotes may allow a broader search: (( support trade integration theories. ) or ( supply grid irrigation scheme. )).
• Adding a wildcard symbol may retrieve word variants: (("support trade integration theories.") or ("supply grid irrigation scheme."))*.