Shnek, Z.M., Foley, F.W., LaRocca, N.G., Grodon, W., DeLuca, J.,
Schwartzman, H.G., Halper, J., Lennox, S. & Irvine, J. (1997). Helplessness, self-efficacy, cognitive distortions and depression in MS and spinal cord injury. Annals of behavioral medicine, 19, 287-294.
Sullivan, M.J., Edgley, K., Mikail, S., Dehoux, E. & Fisher, R. (1992).
Psychological correlates of health care utilization in chronic illness. Canadian Journal of Rehabilitation, 6, 13-21.
Surridge, D. (1969). An investigation into some psychiatric aspects of MS.