Perhaps you should try some spelling variations:
"central basic research a series." » "central bank research a series.", "central asia research a series.", "central banks research a series.", "central basic research _ series.", "central basic research data series."
"central de research firm surveys." » "central de research team surveys.", "central de research firm survey.", "central does research firm surveys.", "central key research firm surveys.", "central led research firm surveys.", "centrale des research firm surveys.", "central _ research firm surveys.", "centro de research firm surveys."

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

• Performing a fuzzy search may retrieve terms with similar spellings: (("central basic research a series.") OR ("central de research firm surveys."))~.
• The words AND, OR and NOT may confuse the search; try adding quotes: "((\"central basic research a series.\") OR (\"central de research firm surveys.\"))".
• Removing quotes may allow a broader search: (( central basic research a series. ) OR ( central de research firm surveys. )).
• Adding a wildcard symbol may retrieve word variants: (("central basic research a series.") OR ("central de research firm surveys."))*.