Tychynin, V. A. “Nonlocal Transformations With Additional Variables. Forced Symmetries”. Ukrains’kyi Matematychnyi Zhurnal 74, no. 3 (April 26, 2022): 400–417. Accessed December 5, 2025. https://umj.imath.kiev.ua/index.php/umj/article/view/6995.