@article{JLT_2002_12_2_JLT_2002_12_2_a12,
     author = {S. Azam },
     title = {Extended {Affine} {Root} {Systems}},
     journal = {Journal of Lie theory},
     pages = {515--527},
     publisher = {mathdoc},
     volume = {12},
     number = {2},
     year = {2002},
     url = {http://geodesic.mathdoc.fr/item/JLT_2002_12_2_JLT_2002_12_2_a12/}
}