Sinaga, Lazarus, and Tiolina Evi. “Perception Analysis and Consumer Behaviour on Purchasing Shell Helix Lubricate Oil Product by Pt. Tira Wira Usaha”. British Journal of Marketing Studies 7, no. 4 (July 30, 2019): 59-75. Accessed March 14, 2025. https://bjmsjournal.org/index.php/bjms/article/view/256.