1. Slight head extension;Harrison;Eur Spine J,2001
2. Comparisons of cervical spine curvatures to a theoretical ideal model of the static sagittal cervical spine;Harrison;Spine,1996
3. Evaluation of the assumptions used to derive an ideal normal cervical spine model;Harrison;J Manipulative Physiol Ther,1997
4. Reliability of spinal displacement analysis on plain x-rays;Harrison;J Manipulative Physiol Ther,1998
5. Kapandji IA. The physiology of the joints, vol 3: the trunk and vertebral column. 5th ed. Edinburgh: Churchill Livingstone; 1974. p. 235-6