1. CEBAM, Belgian Centre for Evidence-Based Medicine; Kapucijnenvoer 33, blok J, bus 7001 Leuven Belgium 3000
2. Hospital for Sick Children; Child Health Evaluative Sciences; 555 University Avenue Toronto ON Canada M5G 1X8
3. University of Sydney; NHMRC Clinical Trials Centre; Locked Bag 77 Camperdown NSW Australia 2050