@article{ZNSL_1970_17_a2,
     author = {V. M. Babich},
     title = {Finding of the saddle point for the ease of an ellipses},
     journal = {Zapiski Nauchnykh Seminarov POMI},
     pages = {20--24},
     year = {1970},
     volume = {17},
     language = {ru},
     url = {http://geodesic.mathdoc.fr/item/ZNSL_1970_17_a2/}
}