@article{SM_1969_7_4_a1,
     author = {M. A. Evgrafov and M. M. Postnikov},
     title = {A~property of the {Siegel} modular group},
     journal = {Sbornik. Mathematics},
     pages = {477--489},
     publisher = {mathdoc},
     volume = {7},
     number = {4},
     year = {1969},
     language = {en},
     url = {http://geodesic.mathdoc.fr/item/SM_1969_7_4_a1/}
}