Perhaps you should try some spelling variations:
"process control estadistico methods." » "process control estadisticas metodos.", "proceso control estadistico methods.", "procesal control estadistico methods."
"procesos control statistical methods." » "proceso contra statistical methods.", "procesos contables statistical methods.", "proceso contralos statistical methods.", "procesos control statistics methods.", "procesos control estadisticas methods."

You may be able to get more results by adjusting your search query.

• Performing a fuzzy search may retrieve terms with similar spellings: (("process control estadistico methods.") or ("procesos control statistical methods."))~.
• If you are trying to use Boolean operators, they must be ALL CAPS: (("process control estadistico methods.") OR ("procesos control statistical methods."))*.
• Removing quotes may allow a broader search: (( process control estadistico methods. ) or ( procesos control statistical methods. ))*.