Zontek, E. L., Z. Zontek, and I. Szewczyk. “Identification of Modern Amenities in Accommodation services—Analysis for Polish Business Tourism”. 2018. New Trends and Issues Proceedings on Humanities and Social Sciences, vol. 5, no. 2, Sept. 2018, pp. 74-81, doi:10.18844/prosoc.v5i2.3656.