Comparison of spirometric results obtained from the sitting and standing position in children participating in an epidemiological study - Brożek, Grzegorz M.; Zejda, Jan E.; Jarosińska, Agnieszka; Idzik, Agnieszka; Lawson, Joshua; Barański, Kamil (Advances in Dermatology and Allergology/Postępy Dermatologii i Alergologii, 2018)