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

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 asia research team series.") OR ("central a research force survey."))~.
• Removing quotes may allow a broader search: (( central asia research team series. ) or ( central a research force survey. ))~.
• Adding a wildcard symbol may retrieve word variants: (("central asia research team series.") or ("central a research force survey."))*.