Bradley RH, National Institute of Child Health and Human Development (NICHD) Early Child Care Research Network, McLeod LD. Child care and common communicable illnesses in children aged 37 to 54 months. Arch Pediatr Adolesc. 2003 Feb;157(2):196-200. doi: 10.1001/archpedi.157.2.196
Bonfill X, Rivero E, Moreno C, Rué M. Changes in cancer mortality in Catalonia and Spain (1975-77 and 1987-89). A comparison with other European countries. Eur J Cancer Prev. 1995 Dec;4(6):453-8.