@article{MZM_1975_18_5_a1,
     author = {V. I. Ivanov},
     title = {Direct and converse theorems of the theory of approximation in the metric of $L_p$ for $0<p<1$},
     journal = {Matemati\v{c}eskie zametki},
     pages = {641--658},
     publisher = {mathdoc},
     volume = {18},
     number = {5},
     year = {1975},
     language = {ru},
     url = {http://geodesic.mathdoc.fr/item/MZM_1975_18_5_a1/}
}