CVEJIĆ, A. Samodurov, S. METHOD OF VARIATION OF PARAMETERS IS NOT EXHAUSTED. Matematichki Bilten, [S. l.], v. 15, n. 1, 1991. Disponível em: https://bilten.smm.org.mk/index.php/bilten/article/view/1494. Acesso em: 13 jun. 2026.