Perhaps you should try some spelling variations:
"structural foundations" » "structural fluctuations", "structural equations", "cultural foundations"
"structural conditions" » "structural transitions", "structural considerations", "structural control"
"structural functional" » "structure functions"

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