@article{TRSPY_1973_132_a14,
     author = {J. W. S. Cassels},
     title = {On sums of squares},
     journal = {Informatics and Automation},
     pages = {114--117},
     publisher = {mathdoc},
     volume = {132},
     year = {1973},
     language = {ru},
     url = {http://geodesic.mathdoc.fr/item/TRSPY_1973_132_a14/}
}