Perhaps you should try some spelling variations:
"central basic research nejm series." » "central based research nejm series.", "central asia research nejm series.", "central bajio research nejm series.", "neutral basic research nejm series.", "central basic research new series.", "central basic research need series.", "central basic research needs series."
"central la research field surveys." » "central la research field survey.", "central la research firm surveys.", "central sla research field surveys.", "central a research field surveys.", "central icla research field surveys.", "central law research field surveys.", "central laos research field surveys.", "central man research field surveys."

Try widening your search to All Fields.

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