@article{ZNSL_1986_151_a6,
     author = {A. N. Karpov},
     title = {On the representation of numbers by integral isotropic quadratic forms},
     journal = {Zapiski Nauchnykh Seminarov POMI},
     pages = {66--67},
     publisher = {mathdoc},
     volume = {151},
     year = {1986},
     language = {ru},
     url = {http://geodesic.mathdoc.fr/item/ZNSL_1986_151_a6/}
}