The label of the x-axis is \(\beta_1\) for squared skewness and
\(\sqrt{\beta_1}\) for regular skewness. The label of the
y-axis is \(\beta_2\).
References
[1] Johnson, N. L., Kotz, S. and Balakrishnan, N. (1994) Continuous Univariate
Distributions, Vol. 1, Wiley Series in Probability and Mathematical Statistics,
Wiley