Perhaps you should try some spelling variations:
fixed investment » direct investment
investment codes » investment code, investment models, investment costs
investor demand » investment demand
rates investor » private investor, rates investment
test fixed » net fixed, testing fixed
heat rates » heat rate, death rates, heat waves

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

• Performing a fuzzy search may retrieve terms with similar spellings: (( h. test fixed investment codes ) or ( h. heat rates investor demand ))~.
• If you are trying to use Boolean operators, they must be ALL CAPS: (( h. test fixed investment codes ) OR ( h. heat rates investor demand ))*.