AHMED, Jamshad; HUSSAIN, Faizan. Analytical solution of system of differential equations by variational iteration method. BIBECHANA, [S. l.], v. 13, p. 77–86, 2015. DOI: 10.3126/bibechana.v13i0.13394. Disponível em: https://www.nepjol.info/index.php/BIBECHANA/article/view/13394. Acesso em: 5 dec. 2025.