@article{DAN_1991_318_3_a17,
     author = {L. G. Kachurin and B. Kh. Petkov},
     title = {Transformation of optical radiation upon propagation through
},
     journal = {Doklady Akademii Nauk},
     pages = {586--589},
     publisher = {mathdoc},
     volume = {318},
     number = {3},
     year = {1991},
     language = {ru},
     url = {http://geodesic.mathdoc.fr/item/DAN_1991_318_3_a17/}
}