@article{GDZPPN002541580, title = {Vector valued Chebechev systems}, journal = {Revista colombiana de matematicas}, volume = {23}, year = {1989}, pages = {25-34}, zbl = {0718.41034}, url = {http://dml.mathdoc.fr/item/GDZPPN002541580} }
Al-Zamel, A.; Khalil, R. Vector valued Chebechev systems. Revista colombiana de matematicas, Tome 23 (1989) pp. 25-34. http://gdmltest.u-ga.fr/item/GDZPPN002541580/