@article{DAN_1983_270_5_a0,
     author = {A. M. Astashov},
     title = {Normal forms of {Hamiltonian} operators in field theory},
     journal = {Doklady Akademii Nauk},
     pages = {1033--1037},
     publisher = {mathdoc},
     volume = {270},
     number = {5},
     year = {1983},
     language = {ru},
     url = {http://geodesic.mathdoc.fr/item/DAN_1983_270_5_a0/}
}