MUHAMMAD, ZULKIFLI, and Wardi Wan Mohd. “Improvement Of Stair Climbing Trolley”. Progress in Engineering Application and Technology 4, no. 1 (May 25, 2023): 714–722. Accessed July 18, 2024. https://publisher.uthm.edu.my/periodicals/index.php/peat/article/view/10345.