Perhaps you should try some spelling variations:
"state reactors" » "state reactor", "state reactions", "state actors"
"state vectors" » "state vector", "state actors", "state detectors"
"state action" » "state reactions", "state actors"

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