Perhaps you should try some spelling variations:
"structural fluctuations" » "structural equations", "structural alterations", "statistical fluctuations"
"structural foundations" » "structural conditions", "structural equations", "cultural foundations"
"structural functions" » "structural functional", "structure functions", "structure function"
"structures functions" » "structure functions", "structure function", "structure functional"

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: (((("structural functions") OR ((("structural foundations") OR ("structural fluctuations"))))) OR ("structures functions")).
• The words AND, OR and NOT may confuse the search; try adding quotes: "((((\"structural functions\") or (((\"structural foundations\") OR (\"structural fluctuations\"))))) or (\"structures functions\"))".
• Removing quotes may allow a broader search: (((( structural functions ) or ((( structural foundations ) OR ( structural fluctuations ))))) or ( structures functions )).
• Adding a wildcard symbol may retrieve word variants: (((("structural functions") or ((("structural foundations") OR ("structural fluctuations"))))) or ("structures functions"))*.