Perhaps you should try some spelling variations:
"supply trade integrationstheorie 2." » "supply der integrationstheorie 2.", "supply eine integrationstheorie 2.", "supply traditionelle integrationstheorie 2.", "supply trade integrationstheorie fur.", "supply trade integration theories.", "supply trade interpretationstheorie 2.", "supply case integrationstheorie 2."
"supply uk immigration policies." » "supply uk immigration policy.", "supply uk migration policy.", "supply u.s immigration policies.", "supply _ immigration policies.", "supply 2 immigration policies.", "supply a immigration policies."

Try widening your search to All Fields.

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

• Performing a fuzzy search may retrieve terms with similar spellings: (("supply trade integrationstheorie 2.") or ("supply uk immigration policies."))~.
• If you are trying to use Boolean operators, they must be ALL CAPS: (("supply trade integrationstheorie 2.") OR ("supply uk immigration policies.")).
• Removing quotes may allow a broader search: (( supply trade integrationstheorie 2. ) or ( supply uk immigration policies. )).
• Adding a wildcard symbol may retrieve word variants: (("supply trade integrationstheorie 2.") or ("supply uk immigration policies."))*.