@article{ZNSL_1972_25_a6,
     author = {V. F. Lazutkin and N. V. Svanidze},
     title = {On that how the general ellipcity property of ray sistems for two mirror resonators is connected with their spectra},
     journal = {Zapiski Nauchnykh Seminarov POMI},
     pages = {111--115},
     publisher = {mathdoc},
     volume = {25},
     year = {1972},
     language = {ru},
     url = {http://geodesic.mathdoc.fr/item/ZNSL_1972_25_a6/}
}