Berezansky, Y.M. and Gekhtman, M.I. (1990) “Inverse problem of spectral analysis and the non-Abelian chains of nonlinear equations ”, Ukrains’kyi Matematychnyi Zhurnal, 42(6), pp. 730–747. Available at: https://umj.imath.kiev.ua/index.php/umj/article/view/8829 (Accessed: 6 December 2025).