@article{SM_2003_194_7_a0,
     author = {M. O. Avdeeva and V. A. Bykovskii},
     title = {An analogue of {Vahlen's} theorem for simultaneous
},
     journal = {Sbornik. Mathematics},
     pages = {955--967},
     publisher = {mathdoc},
     volume = {194},
     number = {7},
     year = {2003},
     language = {en},
     url = {http://geodesic.mathdoc.fr/item/SM_2003_194_7_a0/}
}