Perhaps you should try some spelling variations:
"central s.asi_ research team series." » "central basic research team series.", "central asia research team series.", "central s.a research team series.", "central s.asi_ research areas series.", "central s.asi_ research a series."
"central taxes research firm survey." » "central tax research firm survey.", "central aids research firm survey.", "central does research firm survey.", "central banks research firm survey.", "federal taxes research firm survey.", "central taxes research force survey."

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

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