title: [Effectiveness of biological agents in ankylosing spondylitis].
authors.affiliation: Hospital General de México. Universidad Nacional Autónoma de México. México DF. México.
authors.forename: R
authors.initials: R
authors.lastname: Burgos-Vargas
authors.forename: J
authors.initials: J
authors.lastname: Braun
authors.forename: J C
authors.initials: JC
authors.lastname: Casasola-Vargas
authors.forename: J
authors.initials: J
authors.lastname: Sieper