</math> <ref>S. Foss, D. Korshunov, S. Zachary, ''An Introduction to Heavy-Tailed and Subexponential Distributions'', Springer Science & Business Media, 21 May 2013</ref> | </math> <ref>S. Foss, D. Korshunov, S. Zachary, ''An Introduction to Heavy-Tailed and Subexponential Distributions'', Springer Science & Business Media, 21 May 2013</ref> |