Supriyatno, Dadang, et al. “Velocity Maximum Speed Analysis on Blackspot Area in Basuki Rachmad Krian - Balongbendo Sidoarjo, Indonesia”. International Journal of Engineering & Technology, vol. 7, no. 3.25, Aug. 2018, pp. 437-40, https://doi.org/10.14419/ijet.v7i3.25.17726.