Karunananttha Gunasegeran, and Mohd Hakimi Bin Zohari. “IOT Based Outdoor Manhole Detection and Monitoring System”. Progress in Engineering Application and Technology, vol. 6, no. 2, Oct. 2025, pp. 225-34, https://publisher.uthm.edu.my/periodicals/index.php/peat/article/view/21062.