@Article{zbMATH03095564,
Author = {John {Williamson}},
Title = {{Hadamard's determinant theorem and the sum of four squares}},
FJournal = {{Duke Mathematical Journal}},
Journal = {{Duke Math. J.}},
ISSN = {0012-7094; 1547-7398/e},
Volume = {11},
Pages = {65--81},
Year = {1944},
Publisher = {Duke University Press, Durham, NC; University of North Carolina, Chapel Hill, NC},
Language = {English},
Zbl = {0060.03202}
}