@article{DAN_1973_208_5_a4,
     author = {\`E. I. Kasimov},
     title = {On a basic system},
     journal = {Doklady Akademii Nauk},
     pages = {1023--1025},
     publisher = {mathdoc},
     volume = {208},
     number = {5},
     year = {1973},
     language = {ru},
     url = {http://geodesic.mathdoc.fr/item/DAN_1973_208_5_a4/}
}