Hypersensitivity of azo dyes in urticaria patients based on a single-blind, placebo-controlled oral challenge - Sadowska, Beata; Gawinowska, Marika; Sztormowska, Marlena; Chełmińska, Marta (Advances in Dermatology and Allergology/Postępy Dermatologii i Alergologii, 2022)