1. Research methods in health: Investigating health and health services;Bowling,2014
2. Sampling techniques;Cochran,2007
3. Sampling with varying probabilities without replacement: Rotating and non-rotating samples;Fellegi;Journal of the American Statistical Association,1963
4. Snowball sampling;Goodman;The Annals of Mathematical Statistics,1961
5. A method of sampling with probability exactly proportional to size;Grundy;Journal of the Royal Statistical Society. Series B,1954