Perhaps you should try some spelling variations:
investment series » investment services, investment barriers, investment treaties
trade investment » private investment, estate investment, trade adjustment
scale investment » estate investment, estate investments
investment flows » investment funds
kept trade » net trade, west trade

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

• Performing a fuzzy search may retrieve terms with similar spellings: (( h. kept trade investment series ) or ( h. likert scale investment flows ))~.
• If you are trying to use Boolean operators, they must be ALL CAPS: (( h. kept trade investment series ) OR ( h. likert scale investment flows )).
• Adding a wildcard symbol may retrieve word variants: (( h. kept trade investment series ) or ( h. likert scale investment flows ))*.