Perhaps you should try some spelling variations:
"proceso control estadistica con." » "proceso control estadistico con.", "proceso economia estadistica con.", "process control estadistica con.", "proceso contra estadistica con.", "proceso contralos estadistica con.", "proceso control estadistica en.", "proceso control estadistica y.", "proceso control estadistica de."
"procesal control statistical methods." » "process control statistical methods.", "social control statistical methods.", "proceso contra statistical methods.", "procesal control statistics methods.", "procesal 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: (("procesal control statistical methods.") or ("proceso control estadistica con."))~.
• If you are trying to use Boolean operators, they must be ALL CAPS: (("procesal control statistical methods.") OR ("proceso control estadistica con.")).
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• Adding a wildcard symbol may retrieve word variants: (("procesal control statistical methods.") or ("proceso control estadistica con."))*.