References/Notes/Attributions:
Source
Michael Friendly (2000), Visualizing Categorical Data, pages 21–22.
References
R. A. Fisher, A. S. Corbet, C. B. Williams (1943), The relation between the number of species and the number of individuals, Journal of Animal Ecology, 12, 42–58.
M. Friendly (2000), Visualizing Categorical Data. SAS Institute, Cary, NC.