1. Sampling Techniques;Cochran,1977
2. Sampling of Populations: Methods and Applications;Levy,1991
3. Longitudinal data analysis for discrete and continuous outcomes;Zeger;Biometrics,1986
4. Established populations for epidemiologic studies of the elderly: study design and methodology;Comoni-Huntley;Aging (Milano),1993
5. Established Populations for Epidemiologic Studies of the Elderly,1990