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. Online. 10 July 2020. Vol. 10, no. 7, pp. 56-65. [Accessed 27 April 2024]. DOI 10.12775/JEHS.2020.10.07.005.