@article{SM_1970_10_1_a1,
     author = {E. M. Nikishin},
     title = {On~systems of convergence},
     journal = {Sbornik. Mathematics},
     pages = {21--36},
     publisher = {mathdoc},
     volume = {10},
     number = {1},
     year = {1970},
     language = {en},
     url = {http://geodesic.mathdoc.fr/item/SM_1970_10_1_a1/}
}