@article{1250181480, author = {Lewis, D.W.}, title = {Levels of quaternion algebras}, journal = {Rocky Mountain J. Math.}, volume = {19}, number = {4}, year = {1989}, pages = { 787-792}, language = {en}, url = {http://dml.mathdoc.fr/item/1250181480} }
Lewis, D.W. Levels of quaternion algebras. Rocky Mountain J. Math., Tome 19 (1989) no. 4, pp. 787-792. http://gdmltest.u-ga.fr/item/1250181480/