Wan yusoff, Prof. Dr. Haji Wan Sulaiman. “PROFIT AND ADVERTISING RELATIONSHIP BASED ON PRODUCT DIFFERENTIATION”. I-iECONS e-proceedings 10, no. 1 (August 14, 2023): 65–76. Accessed May 30, 2025. https://epiiecons.usim.edu.my/index.php/eproceeding/article/view/74.