Tadee, Suton, and Umarin Pintoptang. 2023. β€œOn the Non-Linear Diophantine Equations $4^{x} - a^{y} = dz^{2}$ and $4^{x} + a^{y} = dz^{2}$”. Thai Journal of Mathematics 21 (3):563–567. https://thaijmath2.in.cmu.ac.th/index.php/thaijmath/article/view/1527.