Vivek Gupta, Tripti Sagar, Dr. Chetan Panse. 2020. “Use of Online Payment Transactions across Tier-1, Tier-2 and Tier-3 Cities in India”. International Journal of Advanced Science and Technology 29 (4s), 3274-82. http://sersc.org/journals/index.php/IJAST/article/view/22720.