Park, Kyoung-Seon, Sung-Hi An, Hyunmyung Kim, Chang-Hyeon Joh, and Wonho Suh. “Spatial Analysis of Subway Ridership: Rainfall and Ridership”. Proceedings of Engineering and Technology Innovation 40 (October 1, 2016): 1-3. Accessed October 24, 2020. http://ojs.imeti.org/index.php/PETI/article/view/241.