@article{IM2_2021_85_2_a2,
     author = {M. G. Grigoryan and L. N. Galoyan},
     title = {Functions universal with respect to the trigonometric system},
     journal = {Izvestiya. Mathematics},
     pages = {241--261},
     year = {2021},
     volume = {85},
     number = {2},
     language = {en},
     url = {http://geodesic.mathdoc.fr/item/IM2_2021_85_2_a2/}
}