Perhaps you should try some spelling variations:
"central a research firm surveys." » "central a research team surveys.", "central a research firm survey.", "central _ research firm surveys.", "central 2 research firm surveys.", "central tax research firm surveys.", "central s.a research firm surveys."
"central asia research a series." » "central basic research a series.", "central cgiar research a series.", "central ii research a series.", "central asia research _ series.", "central asia research data series.", "central asi_ research a series.", "central asi2 research a series.", "central _sia research a series.", "central taxsia research a series.", "central s.asia research a series."

Try widening your search to All Fields.

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

• Performing a fuzzy search may retrieve terms with similar spellings: (("central asia research a series.") or ("central a research firm surveys."))~.
• If you are trying to use Boolean operators, they must be ALL CAPS: (("central asia research a series.") OR ("central a research firm surveys.")).
• Removing quotes may allow a broader search: (( central asia research a series. ) or ( central a research firm surveys. )).
• Adding a wildcard symbol may retrieve word variants: (("central asia research a series.") or ("central a research firm surveys."))*.