Perhaps you should try some spelling variations:
"import trade integration theory." » "import trade integration through.", "import trade information theory.", "import trade integration report.", "export trade integration theory.", "import taxes integration theory.", "import share integration theory."
"import price integration theory." » "import price integration through.", "import price information theory.", "import price integration report.", "import service integration theory.", "import policy integration theory.", "import grid integration theory.", "import prices integration theory.", "export price integration theory.", "export prices integration theory."

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

• Performing a fuzzy search may retrieve terms with similar spellings: (("import trade integration theory.") OR ("import price integration theory."))~.
• The words AND, OR and NOT may confuse the search; try adding quotes: "((\"import trade integration theory.\") OR (\"import price integration theory.\"))".
• Removing quotes may allow a broader search: (( import trade integration theory. ) OR ( import price integration theory. )).
• Adding a wildcard symbol may retrieve word variants: (("import trade integration theory.") OR ("import price integration theory."))*.