@article{MZM_1974_15_3_a4,
     author = {V. I. Ruban},
     title = {Even diameters of the classes $W^{(r)}H_\omega$ in the space $C_2\pi$},
     journal = {Matemati\v{c}eskie zametki},
     pages = {387--392},
     publisher = {mathdoc},
     volume = {15},
     number = {3},
     year = {1974},
     language = {ru},
     url = {http://geodesic.mathdoc.fr/item/MZM_1974_15_3_a4/}
}