@article{01787968, title = {Extended affine root systems.}, journal = {Journal of Lie Theory}, volume = {12}, year = {2002}, pages = {515-527}, zbl = {1014.17020}, language = {en}, url = {http://dml.mathdoc.fr/item/01787968} }
Azam, Saeid. Extended affine root systems.. Journal of Lie Theory, Tome 12 (2002) pp. 515-527. http://gdmltest.u-ga.fr/item/01787968/