Perhaps you should try some spelling variations:
"the frontier functions" » "the wannier functions", "the frontier section"
"the frontiers section" » "the frontier section"
"the frontier second" » "the frontier section"

Try widening your search to All Fields.

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: (("the frontiers section") OR ((("the frontier second") OR ("the frontier functions")))).
• Removing quotes may allow a broader search: (( the frontiers section ) or ((( the frontier second ) or ( the frontier functions )))).
• Adding a wildcard symbol may retrieve word variants: (("the frontiers section") or ((("the frontier second") or ("the frontier functions"))))*.