@article{ZNSL_1981_104_a0,
     author = {V. M. Babich and V. V. Ulin},
     title = {On complex ray solutions and eigenfunctions concentrated in a~neighbourhood of the closed geodesic},
     journal = {Zapiski Nauchnykh Seminarov POMI},
     pages = {6--13},
     publisher = {mathdoc},
     volume = {104},
     year = {1981},
     language = {ru},
     url = {http://geodesic.mathdoc.fr/item/ZNSL_1981_104_a0/}
}