Perhaps you should try some spelling variations:
"generation through" » "integration through", "creation through"
"generation theory" » "generation theorem", "iteration theory", "generation third"
"generative theory" » "generalized theory", "integrative theory", "alternative theory"
"operators theory" » "operator theory"

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: (("operators theory") OR ((((("generation theory") OR ("generative theory"))) OR ("generation through")))).
• The words AND, OR and NOT may confuse the search; try adding quotes: "((\"operators theory\") or (((((\"generation theory\") OR (\"generative theory\"))) or (\"generation through\"))))".
• Removing quotes may allow a broader search: (( operators theory ) or ((((( generation theory ) OR ( generative theory ))) or ( generation through )))).
• Adding a wildcard symbol may retrieve word variants: (("operators theory") or ((((("generation theory") OR ("generative theory"))) or ("generation through"))))*.