1. Baum, D.: Vending machine. In: Dave Baum’s Definitive Guide to LEGO MINDSTORMS, vol. 10, issue no. 1, pp. 32–42. Apress, Berkeley, CA (2017)
2. Naeini, H.S., Mostowfi, S.: Using QUIS as a measurement tool for user satisfaction evaluation (case study: vending machine). Int. J. Inform. Sci. 5(1), 14–23 (2015)
3. Oo1, H.M., Tun1, K.T., Aung2, S.M.: Coin acceptor based vending machine using microcontroller. Int. J. Trend Sci. Res. Dev. (IJTSRD) 3(5) (2019)
4. Masood, M., Masood, Y., Newton, J.T.: Vending machine threat. Brit. Dent. J. 215, 60 (2013)
5. Dua, A., Rustagi, C., Bhardawaj, A.: A novel approach to designing intelligent vending machines. IJITE2(12) (December 2014)