Drobotskaya, I. S. “Analysis of Complete Integrability of a System Inverse to the Nonlinear Benney-Kaup System”. Ukrains’kyi Matematychnyi Zhurnal, vol. 45, no. 3, Mar. 1993, pp. 353–360, https://umj.imath.kiev.ua/index.php/umj/article/view/5816.