@article{TIMM_2010_16_1_a13,
     author = {A. A. Uspenskii and P. D. Lebedev},
     title = {On the set of limit values of local diffeomorphisms in wavefront evolution},
     journal = {Trudy Instituta matematiki i mehaniki},
     pages = {171--185},
     publisher = {mathdoc},
     volume = {16},
     number = {1},
     year = {2010},
     language = {ru},
     url = {http://geodesic.mathdoc.fr/item/TIMM_2010_16_1_a13/}
}