@article{IM2_1984_23_2_a1,
     author = {V. I. Vasyunin and N. K. Nikol'skii},
     title = {Classification of $H^2$-functions according to the degree of their cyclicity},
     journal = {Izvestiya. Mathematics },
     pages = {225--242},
     publisher = {mathdoc},
     volume = {23},
     number = {2},
     year = {1984},
     language = {en},
     url = {http://geodesic.mathdoc.fr/item/IM2_1984_23_2_a1/}
}