Li, Grace M. X., and Arthur L. B. Yang. “On the $e$-Positivity of $(claw, 2K_2)$-Free Graphs”. The Electronic Journal of Combinatorics 28, no. 2 (June 18, 2021): P2.40. Accessed March 29, 2026. https://www.combinatorics.org/ojs/index.php/eljc/article/view/v28i2p40.