Perhaps you should try some spelling variations:
"import policy intervention studies." » "import policy intervention strategies.", "import policy international studies.", "import policy interventions studies.", "important policy intervention studies.", "import price intervention studies."
"import bans integration south." » "import bans integration study.", "import bans integration some.", "import bans integration social.", "import means integration south.", "import banana integration south.", "import urban integration south.", "import taxes integration south."

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: (("import bans integration south.") OR ("import policy intervention studies."))~.
• Removing quotes may allow a broader search: (( import bans integration south. ) or ( import policy intervention studies. ))~.
• Adding a wildcard symbol may retrieve word variants: (("import bans integration south.") or ("import policy intervention studies."))*.