Perhaps you should try some spelling variations:
"central america research focus series." » "central american research focus series.", "central americans research focus series.", "central africa research focus series.", "central america research focus spring."
"central cgiar research firm series." » "central asia research firm series.", "central asian research firm series.", "central city research firm series.", "central cgiar research from series.", "central cgiar research field series.", "central cgiar research final series.", "central cgiar research film series.", "central cgiar research forum series."

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 firm series.") or ("central america research focus series."))~.
• If you are trying to use Boolean operators, they must be ALL CAPS: (("central cgiar research firm series.") OR ("central america research focus series.")).
• Removing quotes may allow a broader search: (( central cgiar research firm series. ) or ( central america research focus series. )).
• Adding a wildcard symbol may retrieve word variants: (("central cgiar research firm series.") or ("central america research focus series."))*.