1. Ageneralisation of sampling without replacement from a finite universe;Horvitz;J. Amer. Statist. Assoc.,1952
2. On sampling without replacment with varying pobabilities;Narain;J. Indian Soc. Agric. Statist.,1951
3. On the estimate of variance in sampling with varying probabilities;Sen;J. Indian Soc. Agric. Statist.,1953
4. Selection without replacement form within strata with probability proportional to size;Yates;J. Roy. Statist. Soc. Ser. B,1953