Perhaps you should try some spelling variations:
"support trade integration theories." » "support trade integration theorems.", "support trade integrationstheorie 2.", "support trade integration theory.", "support trainer integration theories.", "export trade integration theories.", "import trade integration theories."
"support state interaction term." » "support state interactions term.", "support scale interaction term.", "support state intervention term.", "support state interaction _.", "support stage interaction term.", "support staff interaction term.", "support start interaction term."

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

• Performing a fuzzy search may retrieve terms with similar spellings: (("support trade integration theories.") or ("support state interaction term."))~.
• If you are trying to use Boolean operators, they must be ALL CAPS: (("support trade integration theories.") OR ("support state interaction term.")).
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• Adding a wildcard symbol may retrieve word variants: (("support trade integration theories.") or ("support state interaction term."))*.