RT Journal Article SR Electronic T1 Childhood allergies, birth order and family size JF Thorax JO Thorax FD BMJ Publishing Group Ltd and British Thoracic Society SP 3 OP 5 DO 10.1136/thx.2004.039701 VO 61 IS 1 A1 P Cullinan YR 2006 UL http://thorax.bmj.com/content/61/1/3.abstract AB