Amachukwu, N. J., H. O. Obiora-Ilouno, and E. I. Obisue. “Modeling of Extreme Crude Oil Price Using the Generalized Pareto Distribution: Brent and West Texas Benchmark Price”. Earthline Journal of Mathematical Sciences, Vol. 6, no. 2, Apr. 2021, pp. 359-74, doi:10.34198/ejms.6221.359374.