Radicker, A. C., L. Xue, and T. Yolcu. “The Existence and Identification of Strongly Connected Edge Direction Assignments in Bridgeless Graphs and Multigraphs”. International Journal of Maps in Mathematics, vol. 8, no. 2, Sept. 2025, pp. 791-15, https://simadp.com/journalmim/article/view/339.