@article{ZNSL_1975_51_a10,
     author = {S. V. Petras},
     title = {On resonance series separating onto the {\textquotedblleft}nonphysical{\textquotedblright} sheet},
     journal = {Zapiski Nauchnykh Seminarov POMI},
     pages = {155--169},
     year = {1975},
     volume = {51},
     language = {ru},
     url = {http://geodesic.mathdoc.fr/item/ZNSL_1975_51_a10/}
}