Perhaps you should try some spelling variations:
"support trade integration theories." » "support trade integration theory.", "support trade integration through.", "support trade integration efforts.", "export trade integration theories.", "support grant integration theories.", "import trade integration theories."
"supply crowd irrigation systems." » "supply crop irrigation systems.", "supply flood irrigation systems.", "supply from irrigation systems.", "supply growth irrigation systems.", "supply cost irrigation systems.", "supply how irrigation systems.", "supply crowd 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: (("support trade integration theories.") OR ("supply crowd irrigation systems."))~.
• Removing quotes may allow a broader search: (( support trade integration theories. ) or ( supply crowd irrigation systems. ))~.
• Adding a wildcard symbol may retrieve word variants: (("support trade integration theories.") or ("supply crowd irrigation systems."))*.