Perhaps you should try some spelling variations:
"state actions" » "state action", "state reactions", "state functions"
"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 ("state vector"))) OR ((("state actors") OR ("state actions")))).
• Removing quotes may allow a broader search: (((( state actor ) or ( state vector ))) or ((( state actors ) or ( state actions )))).
• Adding a wildcard symbol may retrieve word variants: (((("state actor") or ("state vector"))) or ((("state actors") or ("state actions"))))*.