2 citations to https://www.mathnet.ru/rus/into446

1. I T Habibullin, K I Faizulina, A R Khakimova, “Laplace transformations and sine-Gordon type integrable PDE”, J. Phys. A: Math. Theor., 57:1 (2024), 015203  
2. Alexander G Rasin, Jeremy Schiff, “Symmetry structure of integrable hyperbolic third order equations”, J. Phys. A: Math. Theor., 56:48 (2023), 485204