4Vitter J S. Random sampling with a reservoir [J]. ACM Trans on Mathematical Software, 1985, 11(1): 37-57.
5Cochran W G. Sampling Techniques [M]. 3rd ed. New York: John Wiley & Sons, 1977.
6Levy P S, Lemeshow S. Sampling of Populations" Methods and Applications [M]. New York: John Wiley & Sons, 1991.
7Lohr S L. Sampling: Design and Analysis [M]. Pacific Grove, CA: Duxbury Press, 1999.
8Olken F, Rotem D. Random sampling from B+trees[C] // Proc of the 15th Int Conf on VLDB. San Francisco: Morgan Kaufmann, 1989:269-277.
9Olken F, Rotem D. Sampling from spatial databases [J]. Statistics and Computing, 1995, 5(1): 43-57.
10Gibbons P B, Matias Y. New sampling-based summary statistics for improving approximate query answers [C] // Proc of ACM SIGMOD 1998. New York: ACM, 1998: 331- 342.