@article{ZVMMF_2003_43_6_a8,
     author = {Yu. V. Vassilevski and K. N. Lipnikov},
     title = {Optimal triangulations: existence, approximations, and double differentiation of $P_1$ finite element functions},
     journal = {\v{Z}urnal vy\v{c}islitelʹnoj matematiki i matemati\v{c}eskoj fiziki},
     pages = {866--874},
     publisher = {mathdoc},
     volume = {43},
     number = {6},
     year = {2003},
     language = {ru},
     url = {http://geodesic.mathdoc.fr/item/ZVMMF_2003_43_6_a8/}
}