@article{EXMATH_2007_2007_1_a5,
     author = {Pe\~na, Jos\'e Antonio de la and Skowronski, Andrzej},
     title = {Subestructuras de \'algebras con forma de {Tits} d\'ebilmente no negativa.},
     journal = {Extracta mathematicae},
     pages = {67-81},
     publisher = {mathdoc},
     volume = {22},
     number = {1},
     year = {2007},
     language = {en},
     url = {http://geodesic.mathdoc.fr/item/EXMATH_2007_2007_1_a5/}
}