1. Rudwaleit M, van der Heijde D, Landewé R, Listing J, Akkoc N, Brandt J, et al. The development of Assessment of SpondyloArthritis international Society classification criteria for axial spondyloarthritis (part II): validation and final selection. Ann Rheum Dis. 2009. 68:777–783.

2. Khan MA. HLA-B27 and its subtypes in world populations. Curr Opin Rheumatol. 1995. 7:263–269.

3. Burgos-Vargas R, Vázquez-Mellado J, Cassis N, Duarte C, Casarín J, Cifuentes M, et al. Genuine ankylosing spondylitis in children: a case-control study of patients with early definite disease according to adult onset criteria. J Rheumatol. 1996. 23:2140–2147.

4. Burgos-Vargas R, Naranjo A, Castillo J, Katona G. Ankylosing spondylitis in the Mexican mestizo: patterns of disease according to age at onset. J Rheumatol. 1989. 16:186–191.

5. Kim TH, Jun JB, Jung SS, Lee IH, Bae SC, Yoo DH, et al. Is juvenile onset ankylosing spondylitis different from adult onset ankylosing spondylitis? J Korean Rheum Assoc. 1999. 6:143–148.

6. Lee CH, Lee MS, Kang KY, Mun SJ, Kim JM, Yun HS, et al. Gender differences in clinical features and anti-TNF agent use in Korean ankylosing spondylitis patients. J Rheum Dis. 2012. 19:132–137.

7. Kim TH, Lee IH, Kim BY, Bae SC, Yoo DH, Park CH, et al. A clinical study of 78 cases of ankylosing spondylitis. Korean J Intern Med. 1991. 41:73–80.

8. Feldtkeller E, Bruckel J, Khan MA. Scientific contributions of ankylosing spondylitis patient advocacy groups. Curr Opin Rheumatol. 2000. 12:239–247.

9. Kim TJ, Kim TH. Clinical spectrum of ankylosing spondylitis in Korea. Joint Bone Spine. 2010. 77:235–240.

10. Lee JH, Jun JB, Jung S, Bae SC, Yoo DH, Kim TY, et al. Higher prevalence of peripheral arthritis among ankylosing spondylitis patients. J Korean Med Sci. 2002. 17:669–673.

11. Jung YO, Kim I, Kim S, Suh CH, Park HJ, Park W, et al. Clinical and radiographic features of adult-onset ankylosing spondylitis in Korean patients: comparisons between males and females. J Korean Med Sci. 2010. 25:532–535.