Hin, Tsen Vui, and Nur Ilyani Ramli. “Design and Development of a Non-Volatile Counter for Metered Dose Inhaler (MDI)”. International Journal of Integrated Engineering 10, no. 3 (July 2, 2018). Accessed May 1, 2024. https://penerbit.uthm.edu.my/ojs/index.php/ijie/article/view/2103.