Perhaps you should try some spelling variations:
"export trade integration theories." » "export trade integration theory.", "export trade integration through.", "export trade integration efforts.", "export share integration theories.", "export taxes integration theories.", "export price integration theories."
"export prices integrating services." » "export prices integrated services.", "export prices testing services.", "export prices integrating policies.", "export policies integrating services.", "export prices international services.", "export services integration services.", "import prices integrating services."

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: (("export trade integration theories.") or ("export prices integrating services."))~.
• If you are trying to use Boolean operators, they must be ALL CAPS: (("export trade integration theories.") OR ("export prices integrating services.")).
• Removing quotes may allow a broader search: (( export trade integration theories. ) or ( export prices integrating services. )).
• Adding a wildcard symbol may retrieve word variants: (("export trade integration theories.") or ("export prices integrating services."))*.