References/Notes/Attributions:
Source
M. Friendly (2000), Visualizing Categorical Data, pages 40–42.
References
J. K. Lindsey (1995), Analysis of Frequency and Count Data. Oxford University Press, Oxford, UK.
R. R. Sokal & F. J. Rohlf (1969), Biometry. The Principles and Practice of Statistics. W. H. Freeman, San Francisco, CA.
M. Friendly (2000), Visualizing Categorical Data. SAS Institute, Cary, NC.