Perhaps you should try some spelling variations:
"procesal control estadistico methods." » "procesal control estadisticas metodos.", "process control estadistico methods.", "social control estadistico methods.", "proceso contra estadistico methods."
"proceso control statistical methods." » "process control statistical methods.", "proceso contra statistical methods.", "proceso contralos statistical methods.", "proceso control statistics methods.", "proceso control estadisticas 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: (("procesal control estadistico methods.") OR ("proceso control statistical methods."))~.
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