Perhaps you should try some spelling variations:
"supply trade integration theories." » "supply trade integration theory.", "supply trade integration through.", "supply trade integration efforts.", "supply side integration theories.", "supply case integration theories."
"support worker integrating policies." » "support worker international policies.", "support worker integrating countries.", "support worker immigration policies.", "support market integrating policies.", "support water integrating policies.", "support border integration 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 integration theories.") or ("support worker integrating policies."))~.
• If you are trying to use Boolean operators, they must be ALL CAPS: (("supply trade integration theories.") OR ("support worker integrating policies.")).
• Removing quotes may allow a broader search: (( supply trade integration theories. ) or ( support worker integrating policies. )).
• Adding a wildcard symbol may retrieve word variants: (("supply trade integration theories.") or ("support worker integrating policies."))*.