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Williams DA, Urban B, Keefe FJ, Shutty MS, France R.Williams DA, et al.Pain. 1995 Apr;61(1):81-91. doi: 10.1016/0304-3959(94)00165-B.Pain. 1995.PMID: 7644252Free article.
France RD, Skott A, Krishnan KR, Urban B, Houpt JL.France RD, et al.South Med J. 1988 Apr;81(4):485-8. doi: 10.1097/00007611-198804000-00019.South Med J. 1988.PMID: 3358174