@article{MZM_1989_46_3_a7,
     author = {Zh. V. Piyadina},
     title = {An analog of the {Hardy{\textendash}Littlewood} equation},
     journal = {Matemati\v{c}eskie zametki},
     pages = {58--67},
     year = {1989},
     volume = {46},
     number = {3},
     language = {ru},
     url = {http://geodesic.mathdoc.fr/item/MZM_1989_46_3_a7/}
}