Classifying the severity of COPD: Are the new severity scales better than the old?

1. Esteban, C.
2. Quintana, J.M.
3. Egurrola, M.
4. Moraza, J.
5. Aburto, M.
6. Pérez-Izquierdo, J.
7. Basualdo, L.V.
8. Capelastegui, A.