Norkin, V.I. “Substantiation of the Backpropagation Technique via the Hamilton—Pontryagin Formalism for Training Nonconvex Nonsmooth Neural Networks”. Reports of the National Academy of Sciences of Ukraine, no. 12 (December 28, 2019): 19–26. Accessed June 19, 2026. https://nasu-periodicals.org.ua/index.php/dp/article/view/2519.