Perhaps you should try some spelling variations:
"support policy integration theories." » "support policy integration theorems.", "support policy integrationstheorie 2.", "support policy integration theory.", "support political integration theories.", "support policy international theories.", "support policy intervention theories.", "support policies integration theories.", "import policy integration theories."
"support better irrigation schemes." » "support better irrigation scheme.", "support better irrigation systems.", "support water irrigation schemes.", "support border irrigation schemes.", "support petite irrigation schemes."

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

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