References
- Burr, I. W. (1969). “Control Charts for Measurements with Varying Sample Sizes”. Journal of Quality Technology 1, pp. 163–167.
- Nelson, L. S. (1989). “Standardization of Shewhart Control Charts”. Journal of Quality Technology 21, pp. 287–289.
- Nelson, L. S. (1990). “Setting Up a Control Chart Using Subgroups of Varying Sizes”. Journal of Quality Technology 22, pp. 245–246.