Hutem, Artit, and Sanit Suwanwong. 2026. “Small Radial of Stable Circular Orbit Perturbations and Effective Potential of a Charged Particle in a Central Force Field: f(r)=-k/r^2 - Eo/r^4 Using Polar Coordinates”. Journal of Science and Technology CRRU 5 (1). Chiangrai, Thailand:64-76. https://li01.tci-thaijo.org/index.php/jstcrru/article/view/270633.