Goodarzi, Khodayar, and M. Nadjafikhah *. 2022. “λ-Symmetry and Integrating Factor For X ̈(f(t,x)+g(t,x)x ̇)e^x: Mathematics, Symmetry”. Hyperscience International Journal 2 (1):7-13. https://doi.org/10.55672/hij2022pp7-13.