University of Kashan Iranian Journal of Mathematical Chemistry 2228-6489 15 1 2024 03 01 Improved Estimates of Sombor Index 1 5 114238 10.22052/ijmc.2023.253825.1782 EN Ivan Gutman Faculty of Science, University of Kragujevac, Kragujevac, Serbia Journal Article 2023 11 05 ‎The Sombor index $(SO)$ is a recently invented vertex-degree-based molecular structure-descriptor‎. ‎Let $M_1$ be the first Zagreb index‎. ‎The fact that $SO$ is bounded from below by $M_{1}/\sqrt{2}$ and from above by $M_{1}$ is well-known and easy to prove‎. ‎In this paper‎, ‎we improve these bounds‎. https://ijmc.kashanu.ac.ir/article_114238_b488c8c6facd0966648ca8841f4d2081.pdf