Perhaps you should try some spelling variations:
"generation theorem" » "separation theorem", "preparation theorem", "generation through"
"generation theory" » "generative theory", "iteration theory", "integration theory"
"operators theory" » "operator theory"
"generation third" » "interaction third"

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