More Groups
Fewer Groups
More People
Fewer People
More Years
Fewer Years
Shapiro, S.; Kelly, J. P.; Rosenberg, L.; Kaufman, D. W.; Helmrich, S. P.; Rosenshein, N. B.; Lewis, J. L. Jr; Knapp, R. C.; Stolley, P. D.; Schottenfeld, D. New England Journal of Medicine (1985)