Perhaps you should try some spelling variations:
"policy international migration soziale." » "policy international cooperation soziale.", "policy interventions migration soziale.", "policy intervention migration soziale.", "policy international migration social.", "policy international migration sowie.", "policy international integration soziale."
"supply trade integration theories." » "supply trade integration theorems.", "supply trade integrationstheorie 2.", "supply trade integration theory.", "supply case integration theories."

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: (("supply trade integration theories.") OR ("policy international migration soziale."))~.
• Removing quotes may allow a broader search: (( supply trade integration theories. ) or ( policy international migration soziale. ))~.
• Adding a wildcard symbol may retrieve word variants: (("supply trade integration theories.") or ("policy international migration soziale."))*.