Perhaps you should try some spelling variations:
"process control statistics methods." » "process control statistical methods.", "process control estadistico methods.", "process control estadistica methods.", "process control statistics methodology.", "procesos control statistics methods.", "proceso control statistics methods.", "procesal control statistics methods."
"social control statistics methods." » "social control statistical methods.", "social control estadistico methods.", "social control estadistica methods.", "social control statistics methodology."

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: (("process control statistics methods.") OR ("social control statistics methods."))~.
• Removing quotes may allow a broader search: (( process control statistics methods. ) or ( social control statistics methods. ))~.
• Adding a wildcard symbol may retrieve word variants: (("process control statistics methods.") or ("social control statistics methods."))*.