Perhaps you should try some spelling variations:
"proceso contra estadisticas methods." » "proceso contra estadisticas metodos.", "proceso contra statistical methods.", "proceso contra estadisticas datos.", "proceso control estadistica methods.", "proceso economia estadisticas methods.", "proceso control estadistico methods."
"process control statistics methods." » "process control statistical methods.", "process control estadistico methods.", "process control estadistica methods.", "process control statistics methodology.", "procesos control statistics methods.", "procesal control statistics methods."

Try widening your search to All Fields.

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