@article{ZNSL_1981_104_a4,
     author = {V. S. Buldyrev and N. S. Grigor'ev},
     title = {The two-scales expansions method for the refractive waveguide},
     journal = {Zapiski Nauchnykh Seminarov POMI},
     pages = {33--48},
     publisher = {mathdoc},
     volume = {104},
     year = {1981},
     language = {ru},
     url = {http://geodesic.mathdoc.fr/item/ZNSL_1981_104_a4/}
}