J. M. Suvisaari et al. “Decline in the Incidence of Schizophrenia in Finnish Cohorts Born from 1954 to 1965”. Archives of General Psychiatry 56, № 8 (1999); J. Suvisaari et al. “Association between Prenatal Exposure to Poliovirus Infection and Adult Schizophrenia”. American Journal of Psychiatry 156, № 7 (1999).