Alhajjar, Mhaid Mhdi, Amaresh Chandra Panda, and Siva Prasad Behera. “A Survey on the Crossing Number Problem”. A Survey on the Crossing Number Problem (March 14, 2023): 1–52. Accessed June 9, 2026. https://stm.bookpi.org/ASCNP/article/view/9924.