Safri, Amin, et al. “Consumer Perception and Expectation on Sharia Bank’s Product Differentiator a Study for Bank DKI Syariah”. Journal of Business Strategy and Execution, vol. 5, no. 1, Nov. 2012, pp. 1-38, https://journal.binus.ac.id/index.php/JBSE/article/view/456.