1. Billingsley, P.: The Lindeberg-Lévy theorem for martingales. Proc. Amer. math. Soc. 12, 788?792 (1961).
2. Doob, J. L.: Stochastic processes. New York: John Wiley & Sons 1953.
3. Garabedian, P. R.: Partial differential equations. New York: John Wiley & Sons 1964.
4. Gnedenko, B. W., and A. N. Kolmogorov: Grenzverteilungen von Summen unabhÄngiger Zufallsgrö\en. Berlin: Akademie-Verlag 1959.
5. Hájek, J.: Limiting distributions in simple random sampling from a finite population. Publ. math. Inst. Hungar. Acad. Sci. Ser. B 5, 361?374 (1960).