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