@article{CRMATH_2011__349_5-6_239_0,
     author = {James O'Shea},
     title = {Sums of squares in certain quaternion and octonion algebras},
     journal = {Comptes Rendus. Math\'ematique},
     pages = {239--242},
     publisher = {Elsevier},
     volume = {349},
     number = {5-6},
     year = {2011},
     doi = {10.1016/j.crma.2011.01.022},
     language = {en},
}