AndreevK. N., and KhruslovE. Y. “Regularized Integrals of Motion for the Korteweg – De-Vries Equation in the Class of Nondecreasing Functions”. Ukrains’kyi Matematychnyi Zhurnal, Vol. 67, no. 12, Dec. 2015, pp. 1587-01, https://umj.imath.kiev.ua/index.php/umj/article/view/2093.