Perhaps you should try some spelling variations:
"state action" » "state reactions", "state actors"
"state sector" » "estate sector", "state vectors", "state section"
"state vector" » "space vector"
"state actor" » "state actors", "state acts", "state vectors"

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: (((((("state actor") OR ("state action"))) OR ((("state sector") OR ("state vector"))))) OR ("state after")).
• Removing quotes may allow a broader search: (((((( state actor ) or ( state action ))) or ((( state sector ) or ( state vector ))))) or ( state after )).
• Adding a wildcard symbol may retrieve word variants: (((((("state actor") or ("state action"))) or ((("state sector") or ("state vector"))))) or ("state after"))*.