2 citations to https://www.mathnet.ru/rus/smj3233

1. Vladimir Romanov, Alemdar Hasanov, “Recovering a potential in damped wave equation from Neumann-to-Dirichlet operator”, Inverse Problems, 36:11 (2020), 115011  
2. Manmohan Vashisth, “An inverse problem for the wave equation with source and receiver at distinct points”, Journal of Inverse and Ill-posed Problems, 27:6 (2019), 835