@article{DAN_1986_286_4_a18,
     author = {M. V. Karasev},
     title = {Hidden symmetry of a system of equations of nonlinear optics. {Hysteresis}},
     journal = {Doklady Akademii Nauk},
     pages = {852--856},
     year = {1986},
     volume = {286},
     number = {4},
     language = {ru},
     url = {http://geodesic.mathdoc.fr/item/DAN_1986_286_4_a18/}
}