Perhaps you should try some spelling variations:
"import data integration theories." » "import data integration theory.", "import data integration through.", "import data integration efforts.", "import trade integration theories.", "import _ integration theories.", "import data integrity theories.", "import duty integration theories."
"import data integration schemes." » "import data irrigation schemes.", "import data integration some.", "import trade integration schemes.", "import _ integration schemes.", "import data integrity schemes.", "import duty integration schemes."

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

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