1. Ecologic studies in epidemiology: concepts, principles, and methods;Morgenstern;Annu Rev Public Health,1995
2. Domestic water and dental caries, V: additional studies of the relation of fluoride domestic waters to dental caries experience in 4,425 white children, aged 12 to 14 years, of 13 cities in 4 states;Dean;Public Health Rep,1942
3. Domestic water and dental caries, II: a study of 2,832 white children, aged 12–14 years, of 8 suburban Chicago communities, including Lactobacillus acidophilis studies of 1,761 children;Dean;Public Health Rep,1941
4. A review of multilevel theory for ecologic analyses;Greenland;Stat Med,2002
5. Multilevel statistical models;Goldstein,2011