AGGARWAL, G. K. An amplifier for fourth order systems. Defence Science Journal, [S. l.], v. 13, n. 4, p. 257–262, 2014. DOI: 10.14429/dsj.13.7109. Disponível em: https://publications.drdo.gov.in/ojs/index.php/dsj/article/view/7109. Acesso em: 11 sep. 2025.