Perhaps you should try some spelling variations:
"exports ratio integration theories." » "exports ratio integration theorems.", "exports ratio integrationstheorie 2.", "exports ratio integration theory.", "exports data integration theories.", "exports carlo integration theories.", "exports facto integration theories.", "export ratio integration theories.", "export ratios integration theories.", "exports latin integration theories."
"import duty banking series." » "import duty banking services.", "import duty making series.", "import duty banking service.", "import bust banking series.", "import der banking series.", "import industry banking series.", "import duties banking series."

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

• Performing a fuzzy search may retrieve terms with similar spellings: (("exports ratio integration theories.") or ("import duty banking series."))~.
• If you are trying to use Boolean operators, they must be ALL CAPS: (("exports ratio integration theories.") OR ("import duty banking series.")).
• Removing quotes may allow a broader search: (( exports ratio integration theories. ) or ( import duty banking series. )).
• Adding a wildcard symbol may retrieve word variants: (("exports ratio integration theories.") or ("import duty banking series."))*.