1. A. N. Tikhonov and A. A. Samarskii, Equations of Mathematical Physics (Nauka, Moscow, 2004) [in Russian].
2. A. G. Fatianov, Dokl. Akad. Nauk 310 (2), 323–327 (1990).
3. A. G. Fatyanov and V. Yu. Burmin, Geofiz. Protsessy Biosfera 20 (1), 61–67 (2021).
4. A. G. Fatyanov and V. Yu. Burmin, Dokl. Earth Sci. 489 (1), 1313–1318 (2019).
5. Wenbo Wu, Sidao Ni, Zhongwen Zhan, and Shengji Wei, Geophys. J. Int. 215 (1), 133–154 (2018).