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Sample Survey Methods and Theory: vol. 1, Methods and Applications; vol. 2, Theory. By M. H. Hansen, W. N. Hurwitz and W. G. Madow. ISBN 0 471 30966 4, 0 471 30967 2. Wiley, New York, 1993. 638 pp. £32.50.
Fielding et al. (Sun,) studied this question.