@article{SM_1996_187_12_a3,
     author = {V. N. Sorokin},
     title = {A transcendence measure for $\pi^2$},
     journal = {Sbornik. Mathematics},
     pages = {1819--1852},
     year = {1996},
     volume = {187},
     number = {12},
     language = {en},
     url = {http://geodesic.mathdoc.fr/item/SM_1996_187_12_a3/}
}