Amanathulla, S., B. Bera, and M. Pal. “L(2,1,1)-Labeling of Circular-Arc Graphs”. Journal of Scientific Research 13, no. 2 (May 1, 2021): 537–544. Accessed December 19, 2024. https://banglajol.info/index.php/JSR/article/view/50483.