@article{SM_2004_195_10_a4,
     author = {I. A. Cheltsov},
     title = {Double space with double line},
     journal = {Sbornik. Mathematics},
     pages = {1503--1544},
     publisher = {mathdoc},
     volume = {195},
     number = {10},
     year = {2004},
     language = {en},
     url = {http://geodesic.mathdoc.fr/item/SM_2004_195_10_a4/}
}