@article{VMP_2015_16_4_a12,
     author = {K. G. Gadylshin and M. I. Protasov},
     title = {Calculation of exact frequency-dependent rays when the solution of the {Helmholtz} equation is known},
     journal = {Numerical methods and programming},
     pages = {586--594},
     publisher = {mathdoc},
     volume = {16},
     number = {4},
     year = {2015},
     language = {ru},
     url = {http://geodesic.mathdoc.fr/item/VMP_2015_16_4_a12/}
}