Kosikowska, Urszula, et al. “Comparison of Colonization of the Upper Respiratory Tract by Haemophilus Influenzae and Staphylococcus Aureus in Healthy Pre-School Children Exposed and Unexposed to Tobacco Smoke”. Current Issues in Pharmacy and Medical Sciences, vol. 23, no. 3, Sept. 2010, pp. 21-25, https://czasopisma.umlub.pl/curipms/article/view/2897.