@article{IM2_2020_84_4_a9,
     author = {V. Sh. Tsagareishvili},
     title = {General orthonormal systems and absolute convergence},
     journal = {Izvestiya. Mathematics },
     pages = {816--828},
     publisher = {mathdoc},
     volume = {84},
     number = {4},
     year = {2020},
     language = {en},
     url = {http://geodesic.mathdoc.fr/item/IM2_2020_84_4_a9/}
}