Perhaps you should try some spelling variations:
"support eu integration theories." » "support eu integration through.", "support eu integration efforts.", "support eu integration reforms.", "support _ integration theories.", "support deep integration theories.", "support data integration theories.", "support key integration theories.", "support a integration theories."
"support staff integration theory." » "support staff integration through.", "support staff information theory.", "support staff integration report.", "support trade integration theory.", "support data integration theory.", "support chain integration theory."

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

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