1. Araki M. Kensetsugyō TQC nyūmon lst Ed. Vol. 2 Shokokusha Publishing Tokyo Japan 1980 p. 55.
2. Araki M. Kensetsugyō no TQC nyūmon 1st Ed. Vol. 2 Shokokusha Publishing Tokyo Japan 1980 p. 59.
3. Araki M. Kensetsugyō no TQC nyūmon 1st Ed. Vol. 2 Shokokusha Publishing Tokyo Japan 1980 p. 60.
4. Asakaoru T. Kensetsugyō no TQC 1st Ed. Vol. 3 Tokyo Japan 1979 pp. 32–33.
5. Barrie D. S. and Paulson B. C. Jr. Professional Construction Management 2nd Ed. McGraw‐Hill New York N.Y. 1984 p. 313.