Perhaps you should try some spelling variations:
"human agents periodicals." » "human aspects periodicals.", "human arts periodicals.", "human plants periodicals.", "human agent periodicals.", "human agency periodicals."
"human gases periodicals." » "human games periodicals.", "human leases periodicals.", "human gas periodicals.", "human cases periodicals.", "human causes periodicals.", "human gamers periodicals."
"human bees periodicals." » "human diabetes periodicals.", "human indexes periodicals.", "human devices periodicals.", "human bites periodicals.", "human beast periodicals.", "human bones periodicals."

Try widening your search to All Fields.

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• Performing a fuzzy search may retrieve terms with similar spellings: (((("human bees periodicals.") or ("human gases periodicals."))) or ("human agents periodicals."))~.
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