Perhaps you should try some spelling variations:
"procesos problems statistics methods." » "procesos problems statistical methods.", "procesos problems statistics methodology.", "procesos process statistics methods.", "procesos penales statistics methods."
"proceso control statistical methods." » "process control statistical methods.", "proceso contra statistical methods.", "proceso contralos statistical methods.", "proceso 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: (("procesos problems statistics methods.") or ("proceso control statistical methods."))~.
• If you are trying to use Boolean operators, they must be ALL CAPS: (("procesos problems statistics methods.") OR ("proceso control statistical methods."))*.
• Removing quotes may allow a broader search: (( procesos problems statistics methods. ) or ( proceso control statistical methods. ))*.