@article{MZM_1980_27_1_a5,
     author = {A. A. Ligun},
     title = {Diameters of certain classes of differentiate periodic functions},
     journal = {Matemati\v{c}eskie zametki},
     pages = {61--75},
     publisher = {mathdoc},
     volume = {27},
     number = {1},
     year = {1980},
     language = {ru},
     url = {http://geodesic.mathdoc.fr/item/MZM_1980_27_1_a5/}
}