CHANG IL KIM, and GILJUN HAN. “ORTHOGONALLY EULER-LAGRANGE TYPE CUBIC FUNCTIONAL EQUATIONS IN ORTHOGONALITY NORMED SPACES”. Journal of Computational Analysis and Applications (JoCAAA) 29, no. 4 (August 10, 2021): 765–774. Accessed December 19, 2024. https://eudoxuspress.com/index.php/pub/article/view/190.