Nancy R. Tague. Seven Basic Quality Tools. The Quality Toolbox. Milwaukee, Wisconsin: American Society for Quality: 15. 2004 [2010-02-05]. (原始内容存档于2018-10-31).
Nancy R. Tague. Seven Basic Quality Tools. The Quality Toolbox. Milwaukee, Wisconsin: American Society for Quality: 15. 2004 [2010-02-05]. (原始内容存档于2018-10-31).