NIEDZIELSKA , Anna. Evolution of Direct Marketing Instruments. Studia Oeconomica Posnaniensia, Poznan, Polska, v. 6, n. 5, p. 57–68, 2017. DOI: 10.18559/SOEP.2018.5.5. Disponível em: https://journals.ue.poznan.pl/soep/article/view/3815. Acesso em: 3 sep. 2026.