1. Twardowski ZJ, Nolph KD, Khanna R et al. Peritoneal equilibration test. Perit Dial Bull 1987; 7(3): 138–47.
2. Conover WJ. Practical nonparametric statistics, 2nd ed. New York: John Wiley & Sons, 1980.
3. Lehmann EL. Nonparametrics: statistical methods based on ranks. San Francisco: Holden-Day, 1975.
4. Friedman GD. Primer of epidemiology. New York: McGraw-Hill, 1974.
5. Monson RR. Occupational epidemiology. Boca Raton: CRC Press, 1980.