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