Samuliak, R. V. “Generalized Dicke Model As an Integrable Dynamical System Inverse to the Nonlinear Schrödinger Equation”. Ukrains’kyi Matematychnyi Zhurnal, vol. 47, no. 1, Jan. 1995, pp. 126–128, https://umj.imath.kiev.ua/index.php/umj/article/view/5393.