Perhaps you should try some spelling variations:
investment series » investment services, investment barriers, investment treaties
investment period » investment policy, adjustment period, investment operations
fixed investment » direct investment
based investment » best investment, bond investment, related investment
test based » text based, rest based, trust based

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 fixed investment series ) or ( h. test based investment period ))~.
• If you are trying to use Boolean operators, they must be ALL CAPS: (( h. agent fixed investment series ) OR ( h. test based investment period )).
• Adding a wildcard symbol may retrieve word variants: (( h. agent fixed investment series ) or ( h. test based investment period ))*.