@article{1077472371, author = {Williamson, John}, title = {Hadamard's determinant theorem and the sum of four squares}, journal = {Duke Math. J.}, volume = {11}, number = {1}, year = {1944}, pages = { 65-81}, language = {en}, url = {http://dml.mathdoc.fr/item/1077472371} }
Williamson, John. Hadamard’s determinant theorem and the sum of four squares. Duke Math. J., Tome 11 (1944) no. 1, pp. 65-81. http://gdmltest.u-ga.fr/item/1077472371/