Perhaps you should try some spelling variations:
"centra asia research team series." » "centra basic research team series.", "centra media research team series.", "centra china research team series.", "central asia research team series.", "central asian research team series.", "century asia research team series.", "centra asia research stem series.", "centra asia research nejm series.", "centra asia research tilsm series."
"central tax research firm surveys." » "central tax research from surveys.", "central tax research field surveys.", "central tax research final surveys.", "central 2 research firm surveys.", "central 2.1 research firm surveys.", "central 2.2 research firm surveys.", "central tax research firm survey.", "central taxes research firm surveys.", "central bank research firm surveys."

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