Susanto, Saskia, and Rini Indahwati. “The Influence of Promotional Mix on Decision Making to Purchase Oppo Brand Cell Phones in Medan City”. Outline Journal of Economic Studies 1, no. 2 (September 29, 2022): 77–89. Accessed October 11, 2025. https://outlinepublisher.com/index.php/OJES/article/view/25.