Acute severe paediatric asthma: study protocol for the development of a core outcome set, a Pediatric Emergency Reserarch Networks (PERN) study. - Craig S; Babl FE; Dalziel SR; Gray C; Powell C; Al Ansari K; Lyttle MD; Roland D; Benito J; Velasco R; Hoeffe J; Moldovan D; et al. (Trials, 2020)