@article{ZNSL_2018_471_a8,
     author = {A. Ya. Kazakov},
     title = {``Separation of variables'' in the model problems of the diffraction theory. {Formal} scheme},
     journal = {Zapiski Nauchnykh Seminarov POMI},
     pages = {124--139},
     publisher = {mathdoc},
     volume = {471},
     year = {2018},
     language = {ru},
     url = {http://geodesic.mathdoc.fr/item/ZNSL_2018_471_a8/}
}