@article{DAN_1989_308_3_a6,
     author = {M. Szyjewski},
     title = {The fifth invariant of quadratic forms},
     journal = {Doklady Akademii Nauk},
     pages = {542--545},
     publisher = {mathdoc},
     volume = {308},
     number = {3},
     year = {1989},
     language = {ru},
     url = {http://geodesic.mathdoc.fr/item/DAN_1989_308_3_a6/}
}