1. Beetham, W. P., Polley, H. F., Slocomb, C. H., and Weaver, W. F. (1966). Physical Examination of the Joints, p. 98. Saunders, Philadelphia.
2. Bennett, P. H., and Wood, P. H. N. (1968). (Editors.) Population Studies of the Rheumatic Diseases, p. 456. International Congress Series, No. 148. Excerpta Medica, Amsterdam.
3. The accuracy of estimating neck movements;Newell, D.J.; Nicholls, P.J.R.;Annals of Physical Medicine,1965
4. Spondylometry in a normal population and in ankylosing spondylitis;Sturrock, R.D.; Wojtulewski, J.A.; Hart, F.D.;Rheumatology and Rehabilitation,1973