Rapiejko , P., A. Lipiec, D. Jurkiewicz, and E. Kalinowska. “Pollen Seasons of Hazel, Alder and Birch in Warsaw in 2014”. Alergoprofil, Vol. 10, no. 2, June 2014, pp. 41-44, https://www.journalsmededu.pl/index.php/alergoprofil/article/view/800.