PANDEY, S. .; OBRADOVIC, D. .; MISHRA, L. . N. .; MISHRA, V. N. Second Order Partial Derivatives . JOURNAL OF ADVANCES IN MATHEMATICS, [S. l.], v. 20, p. 419–423, 2021. DOI: 10.24297/jam.v20i.9097. Disponível em: https://rajpub.com/index.php/jam/article/view/9097. Acesso em: 20 apr. 2024.