Frühwirth, Rudolf, and Wolfgang Waltenberger. “Redescending M-Estimators and Deterministic Annealing, With Applications to Robust Regression and Tail Index Estimation”. Austrian Journal of Statistics 37, no. 3&4 (April 3, 2016): 301–317. Accessed May 9, 2021. https://ajs.or.at/index.php/ajs/article/view/vol37%2C%20no3%264%20-%207.