Perhaps you should try some spelling variations:
"proces muestreo statistical methods." » "proces muestreo estadistica methods.", "proces muestreo estadistico methods.", "proceso muestreo statistical methods.", "roces muestreo statistical methods.", "procesos muestreo statistical methods."
"process control statistics methods." » "process control statistical methods.", "process control estadistico methods.", "process control estadistica methods.", "process control statistics methodology.", "procesos control statistics methods.", "rocess control statistics methods.", "procesoss control statistics methods."

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