Perhaps you should try some spelling variations:
"supply crop irrigation schemes." » "supply crop irrigation scheme.", "supply crop irrigation systems.", "supply drip irrigation schemes.", "supply scale irrigation schemes.", "supply canal irrigation schemes.", "supply crowd irrigation schemes.", "supply from irrigation schemes.", "supply europe irrigation schemes."
"support trade information theory." » "support price information theory.", "support private information theory.", "support trade integration theory.", "support trainer information theory.", "export trade information theory.", "import trade information theory."

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• Performing a fuzzy search may retrieve terms with similar spellings: (("support trade information theory.") or ("supply crop irrigation schemes."))~.
• If you are trying to use Boolean operators, they must be ALL CAPS: (("support trade information theory.") OR ("supply crop irrigation schemes.")).
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• Adding a wildcard symbol may retrieve word variants: (("support trade information theory.") or ("supply crop irrigation schemes."))*.