Perhaps you should try some spelling variations:
"production wannier functions" » "production water functions", "production barrier functions", "production carrier functions", "production inner functions", "production wigner functions"
"production frontier section" » "production frontiers section", "production frontier second", "production frontal sections"
"production frontier region" » "production frontal region"

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: (((("production frontier section") OR ((("production frontier functions") OR ("production wannier functions"))))) OR ("production frontier region")).
• The words AND, OR and NOT may confuse the search; try adding quotes: "((((\"production frontier section\") or (((\"production frontier functions\") OR (\"production wannier functions\"))))) or (\"production frontier region\"))".
• Removing quotes may allow a broader search: (((( production frontier section ) or ((( production frontier functions ) OR ( production wannier functions ))))) or ( production frontier region )).
• Adding a wildcard symbol may retrieve word variants: (((("production frontier section") or ((("production frontier functions") OR ("production wannier functions"))))) or ("production frontier region"))*.