SHEN, Ruxu. Analysis on Perturbation of Ground State Energy for Anharmonic Oscillator and Helium Atom. Highlights in Science, Engineering and Technology, [S. l.], v. 141, p. 53–58, 2025. DOI: 10.54097/6c9bvc68. Disponível em: https://hsetdata.com/index.php/ojs/article/view/646. Acesso em: 24 jun. 2026.