Perhaps you should try some spelling variations:
"human gases periodicals." » "human games periodicals.", "human leases periodicals.", "human gas periodicals.", "human causes periodicals.", "human gamers periodicals.", "human based periodicals."
"human cases periodicals." » "human caves periodicals.", "human classes periodicals.", "human leases periodicals.", "human causes periodicals.", "human case periodicals.", "human caspases periodicals."
"human ages periodicals." » "human agents periodicals.", "human bees periodicals.", "human changes periodicals.", "human age periodicals.", "human images periodicals."

Try widening your search to All Fields.

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

• Performing a fuzzy search may retrieve terms with similar spellings: (((("human gases periodicals.") or ("human cases periodicals."))) or ("human ages periodicals."))~.
• If you are trying to use Boolean operators, they must be ALL CAPS: (((("human gases periodicals.") OR ("human cases periodicals."))) OR ("human ages periodicals.")).
• Removing quotes may allow a broader search: (((( human gases periodicals. ) or ( human cases periodicals. ))) or ( human ages periodicals. )).
• Adding a wildcard symbol may retrieve word variants: (((("human gases periodicals.") or ("human cases periodicals."))) or ("human ages periodicals."))*.