RT Journal Article SR Electronic T1 Changes in asthma prevalence. JF Archives of Disease in Childhood JO Arch Dis Child FD BMJ Publishing Group Ltd and Royal College of Paediatrics and Child Health SP 646 OP 646 DO 10.1136/adc.65.6.646 VO 65 IS 6 A1 E A Mitchell A1 H R Anderson YR 1990 UL http://adc.bmj.com/content/65/6/646.1.abstract AB