Perhaps you should try some spelling variations:
"proceso control estadistico metodos." » "proceso control estadisticas metodos.", "proceso control estadistica estudios.", "proceso contra estadistico metodos.", "proceso contralos estadistico metodos.", "proces contre estadistico metodos."
"process control statistical methods." » "procesos control statistical methods.", "procesal control statistical methods.", "process control statistics methods.", "process 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 statistical methods.") or ("proceso control estadistico metodos."))~.
• If you are trying to use Boolean operators, they must be ALL CAPS: (("process control statistical methods.") OR ("proceso control estadistico metodos.")).
• Removing quotes may allow a broader search: (( process control statistical methods. ) or ( proceso control estadistico metodos. )).
• Adding a wildcard symbol may retrieve word variants: (("process control statistical methods.") or ("proceso control estadistico metodos."))*.