@article{SM_1985_51_1_a7,
     author = {E. P. Golubeva},
     title = {On the length of the period of a~quadratic irrationality},
     journal = {Sbornik. Mathematics},
     pages = {119--128},
     year = {1985},
     volume = {51},
     number = {1},
     language = {en},
     url = {http://geodesic.mathdoc.fr/item/SM_1985_51_1_a7/}
}