Perhaps you should try some spelling variations:
"exaction theory" » "action theory", "reaction theory", "traction theory"
"exact theory" » "effect theory", "exart theory", "exaction theory", "exagent theory"
"act theory" » "art theory", "action theory", "agent 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: (("act theory") OR ((("exact theory") OR ("exaction theory")))).
• The words AND, OR and NOT may confuse the search; try adding quotes: "((\"act theory\") or (((\"exact theory\") OR (\"exaction theory\"))))".
• Removing quotes may allow a broader search: (( act theory ) or ((( exact theory ) OR ( exaction theory )))).
• Adding a wildcard symbol may retrieve word variants: (("act theory") or ((("exact theory") OR ("exaction theory"))))*.