Perhaps you should try some spelling variations:
"central taxes research firm series." » "central tables research firm series.", "central tax research firm series.", "central wages research firm series.", "central taxes research from series.", "central taxes research field series.", "central taxes research final series.", "central banks research firm series.", "federal taxes research firm series.", "central taxes research film series.", "central taxes research forum series."
"central iea research firm survey." » "central iea research from survey.", "central iea research field survey.", "central iea research final survey.", "central a research firm survey.", "central 2 research firm survey.", "central 2.1 research firm survey.", "central idea research firm survey.", "central area research firm survey.", "central de research firm 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 iea research firm survey.") or ("central taxes research firm series."))~.
• If you are trying to use Boolean operators, they must be ALL CAPS: (("central iea research firm survey.") OR ("central taxes research firm series.")).
• Removing quotes may allow a broader search: (( central iea research firm survey. ) or ( central taxes research firm series. )).
• Adding a wildcard symbol may retrieve word variants: (("central iea research firm survey.") or ("central taxes research firm series."))*.