Frallonardo, P., R. Ramonda, A. Lo Nigro, V. Modesti, C. Campana, and L. Punzi. 2011. “The Natural History of Ankylosing Spondylitis in the 21st Century”. Reumatismo 63 (1):49-54. https://doi.org/10.4081/reumatismo.2011.49.