Perhaps you should try some spelling variations:
"proceso control economics methodology." » "proceso cultural economics methodology.", "proceso contextos economicos methodology.", "proceso contra economics methodology.", "proceso contralos economics methodology.", "proces contre economics methodology."
"process control statistical methods." » "procesos control statistical methods.", "procesal control statistical methods.", "process control statistics methods.", "process 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: (("process control statistical methods.") OR ("proceso control economics methodology."))~.
• Removing quotes may allow a broader search: (( process control statistical methods. ) or ( proceso control economics methodology. ))~.
• Adding a wildcard symbol may retrieve word variants: (("process control statistical methods.") or ("proceso control economics methodology."))*.