Perhaps you should try some spelling variations:
investment series » investment services, investment barriers, investment treaties
investment demand » investor demand
based investment » fixed investment, best investment, bond investment
erm investment » term investment, term investments, farm investment
key erm » key term, key terms

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

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