@article{DAN_1989_309_3_a2,
     author = {V. F. Dem'yanov},
     title = {Second-order approximation for a nonsmooth function},
     journal = {Doklady Akademii Nauk},
     pages = {529--532},
     publisher = {mathdoc},
     volume = {309},
     number = {3},
     year = {1989},
     language = {ru},
     url = {http://geodesic.mathdoc.fr/item/DAN_1989_309_3_a2/}
}