ROBUL, Y. Structure and Constituents of Digital Marketing Systems. Olsztyn Economic Journal, [S. l.], v. 15, n. 1, p. 53–62, 2020. DOI: 10.31648/oej.5398. Disponível em: https://czasopisma.uwm.edu.pl/index.php/oej/article/view/5398. Acesso em: 2 dec. 2021.