Greedy Function Approximation: A Gradient Boosting Machine, Jerome H. Friedman, 2001The Annals of Statistics, Vol. 29 (Institute of Mathematical Statistics)DOI: 10.1214/aos/1013203451 - The original research paper introducing the Gradient Boosting Machine algorithm, explaining its mathematical basis and the use of differentiable loss functions.
Robust Statistics, Peter J. Huber, Elvezio M. Ronchetti, 2009 (Wiley)DOI: 10.1002/9780470434259 - This book offers an authoritative discussion of statistical methods for robustness, including the theoretical aspects and characteristics of Huber Loss.