1. Calin A. Ankylosing Spondylitis. In: Textbook of Rheumatology. Eds. Kelley WN, Harris ED Jr, Ruddy S and Sledge CB. Philadelphia, W.B. Saunders Co. 1989:1021–1037.
2. Khan MA. Ankylosing Spondylitis. In: Spondylarthropathies. Ed. Calin A. New York, Grune and Stratton Inc. 1984:69–117.
3. Mander M, Simpson JM, McLellan A, Walker D, Goodacre JA and Dick WC. Studies with an enthesis index as a method of clinical assessment in ankylosing spondylitis. Ann Rheum Dis 1987;46:197–202.
4. Dougados M, Geuguen A, Nakache J-P, Nguyen M, Mery C and Amor B. Evaluation of a functional index and an articular index in ankylosing spondylitis. J Rheumatol 1988;15:302–307.
5. Bellamy N. Colour Atlas of Clinical Rheumatology. Lancaster, MTP Press. 1985:81–93.