[1]
W. Alam, D. Sarma, R. Joyti Chakma, M. J. Alam, and S. Hossain, “Internet of Things Based Smart Vending Machine using Digital Payment System”, IJEEI, vol. 9, no. 3, pp. 719–731, Aug. 2021, doi: 10.52549/.v9i3.3133.