1. Hesselvik, L. Respiratory infections among children in day nurseries. Acta Paediatr. (Stockh.) Suppl. 74 (1949) 1–103.
2. Vihma, L. Surveillance of acute viral respiratory disease in children. Acta Paediatr. Scand. Suppl. 192 (1969) 1–52.
3. Strangert, K. Respiratory illness in preschool children in the different forms of day care. Pediatrics 57 (1976) 191–196.
4. Strangert, K. Otitis media in young children in different types of day care. Scand. J. Infect. Dis. 9 (1977) 119–123.
5. Vinter, B., Elbrönd, O., Brahe Pedersen, C. A population study of otitis media in childhood. Acta Otolaryngol. Suppl. 360 (1979) 135–137.