Perhaps you should try some spelling variations:
"proceso contralos statistical methods." » "proceso control statistical methods.", "proceso contra statistical methods.", "proces contreles statistical methods.", "procesos contables statistical methods."
"process control estadisticas datos." » "process control estadistica datos.", "process control estadistico datos.", "process control statistical datos.", "process control estadistica casos.", "process control estadisticas metodos.", "process control estadisticas de.", "procesos control estadisticas datos.", "procesal control estadisticas datos."

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 estadisticas datos.") or ("proceso contralos statistical methods."))~.
• If you are trying to use Boolean operators, they must be ALL CAPS: (("process control estadisticas datos.") OR ("proceso contralos statistical methods.")).
• Removing quotes may allow a broader search: (( process control estadisticas datos. ) or ( proceso contralos statistical methods. )).
• Adding a wildcard symbol may retrieve word variants: (("process control estadisticas datos.") or ("proceso contralos statistical methods."))*.