Received: 19 July 2021 ; Accepted: 30 August 2021 ; Published: 2 September 2021. This is an open access article distributed under the terms and conditions of the Creative Commons Attribution (CC BY 4.0) license. This article belongs to the Special Issue The New Era of Digital Marketing. The work was supported by the National Science Center (B.K., A.S. and W.S.). The project financed within the framework of the program of the Minister of Science and Higher Education under the name “Regional Excellence Initiative” in the years 2019–2022 (A.B. and J.W.). |
