@article{IM2_1993_41_1_a7,
     author = {S. A. Imomkulov},
     title = {Twice differentiability of subharmonic functions},
     journal = {Izvestiya. Mathematics },
     pages = {157--167},
     publisher = {mathdoc},
     volume = {41},
     number = {1},
     year = {1993},
     language = {en},
     url = {http://geodesic.mathdoc.fr/item/IM2_1993_41_1_a7/}
}