More Groups
Fewer Groups
Schrag, D.; Kuntz, K. M.; Garber, J. E.; Weeks, J. C. JAMA - Journal of the American Medical Association (2000)
Schrag, D.; Cramer, L. D.; Bach, P. B.; Cohen, A. M.; Warren, J. L.; Begg, C. B. JAMA - Journal of the American Medical Association (2000)