Consult the following references:

• Practical Tools for Continuous Improvement, Volume 1 Statistical Tools, PQ Systems, Inc. Copyright 2000. 1-800-777-3020
  
  
• Fundamental Statistical Process Control, AIAG/ASQC Automotive Industry Action Group, American Society for Quality Control, Copyright 1991.
  
  
• TQT Improvement Tools, Total Quality Transformation^®, PQ Systems, Inc. Copyright 1992. 1-800-777-3020
  
  
• TQT Total Quality Tools, Total Quality Transformation, PQ Systems, Inc. Copyright 1992. 1-800-777-3020
  
  
• Beyond Capability Confusion, Donald J. Wheeler, Ph.D. SPC Press, Copyright 1999.

See also:
>> Can a process produce output within specifications?
>> Capability vs control
>> Normal data capability analysis
>> Non-normal data capability analysis
>> What is capability analysis and when is it used?
>> What are the capability indices?