Perhaps you should try some spelling variations:
"central cgiar research _ series." » "central climate research _ series.", "central asia research _ series.", "central asian research _ series.", "central city research _ series."
"central de research force survey." » "central de research focus survey.", "central de research firm survey.", "central de research food survey.", "central does research force survey.", "central key research force survey.", "central led research force survey.", "centrale des research force survey.", "central _ research force survey.", "centro de research force survey."

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

• Performing a fuzzy search may retrieve terms with similar spellings: (("central cgiar research _ series.") or ("central de research force survey."))~.
• If you are trying to use Boolean operators, they must be ALL CAPS: (("central cgiar research _ series.") OR ("central de research force survey."))*.
• Removing quotes may allow a broader search: (( central cgiar research _ series. ) or ( central de research force survey. ))*.