Eriks-Hoogland I, Cieza A, Post MWM, Hilfiker R, Van Hedel H, Cripps R, Chen Y, Boldt C, Stucki G: Category specification and measurement instruments in large spinal cord injury studies: a comparison using the International Classification of Functioning, Disability and Health (ICF) as a reference. In: Amercian Journal of Physical Medicine and Rehabilitation, 2011, 90 (suppl): P. 39-49.