KUZNIETSOVA, Iryna and MAKSYMENKO, Sergiy. Deformational symmetries of smooth functions on non-orientable surfaces. Topological Methods in Nonlinear Analysis. Online. 13 February 2025. Vol. 65, no. 1, pp. 35 - 77. [Accessed 17 January 2026]. DOI 10.12775/TMNA.2024.022.