Perhaps you should try some spelling variations:
"estate sector" » "state section"
"state vector" » "space vector"
"state actor" » "state action", "state sector", "state after"
"state actors" » "state actions", "state sectors", "state afters", "state factors"

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