Gregorova, B., W. Sadkowski, and K. Sala. “Quality Costs in Historic Hospitality During the Covid-19 Pandemic. Case Studies of Jelenia Góra and Banska Bystrzyca”. Studies of the Industrial Geography Commission of the Polish Geographical Society, vol. 37, no. 1, Mar. 2023, pp. 119–131, doi:10.24917/20801653.371.7.