@article{MZM_1991_49_5_a0,
     author = {N. Ainulloev},
     title = {An~exact estimate of the second derivative in $l_p$},
     journal = {Matemati\v{c}eskie zametki},
     pages = {3--6},
     publisher = {mathdoc},
     volume = {49},
     number = {5},
     year = {1991},
     language = {ru},
     url = {http://geodesic.mathdoc.fr/item/MZM_1991_49_5_a0/}
}