4Mitra D, Ring EFJ, BhaHa AK, et al. Osteoporosis as--sociated with ankylosing spondylitis[M]. Current research in osteoporpsis and bone mineral measurement. III. London: British Institute of Radiology, 1994:42 - 43.
5Kahn M A. Ankylosing spondylitis and other spondy-- loathropathies [J]. Rheum Dise Clin North Am, 1990,16:551.