Kowalik, Kamila. “The Importance of Chosen Attributes of a Digital Postal Service in Shaping Its Quality in the Opinion of Customers at the Age of 18-30”. Journal of Education, Health and Sport 10, no. 7 (July 10, 2020): 56–65. Accessed July 1, 2025. https://apcz.umk.pl/JEHS/article/view/JEHS.2020.10.07.005.