Gor’kavyiV. A., and NevmerzhitskayaE. N. “Degenerate Backlund Transformation”. Ukrains’kyi Matematychnyi Zhurnal 68, no. 1 (January 25, 2016): 38-51. Accessed July 27, 2024. https://umj.imath.kiev.ua/index.php/umj/article/view/1820.