The point-source of electromagnetic waves in the case of nonhomogeneous media (high-frequency ansatz and dual to him singular solution)
V. M. Babich

References
1.	V. M. Babich, “O korotkovolnovoi asimptotike resheniya zadachi o tochechnom istochnike kolebanii v neodnorodnoi srede”, Zhurnal vychislitelnoi matematiki i matematicheskoi fiziki, 5:5 (1965), 949–952
2.	Wangtao Lu, Jianliang Qian, Robert Burridge, “Babich-like ansatz for three-dimensional point-source Maxwell's equations in an inhomogeneous medium at high frequencies”, Multiscale Model. Simul., 14:3 (2016), 1089–1122
3.	V. M. Babich, A. P. Kiselev, Uprugie volny. Vysokochastotnaya teoriya, BKhV-Peterburg, SPb., 2014
4.	R. Kurant, Uravneniya s chastnymi proizvodnymi, Mir, Moskva, 1964