Perhaps you should try some spelling variations:
"import trade integration theories." » "import trade integration theorems.", "import trade integrationstheorie 2.", "import trade integration theory.", "export trade integration theories.", "import price integration theories.", "import share integration theories."
"import taxes integration theories." » "import taxes integration theorems.", "import taxes integrationstheorie 2.", "import taxes integration theory.", "import spaces integration theories.", "import values integration theories.", "import res integration theories.", "export taxes integration theories."

Try widening your search to All Fields.

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• Performing a fuzzy search may retrieve terms with similar spellings: (("import trade integration theories.") OR ("import taxes integration theories."))~.
• The words AND, OR and NOT may confuse the search; try adding quotes: "((\"import trade integration theories.\") OR (\"import taxes integration theories.\"))".
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