VAN DER WALT, Bennie. Isaac da Costa (1798-1860) se besware teen die gees van sy tyd. Tydskrif vir Christelike Wetenskap | Journal for Christian Scholarship, [S. l.], v. 53, n. 1, p. 19–58, 2017. Disponível em: https://pubs.ufs.ac.za/index.php/tcw/article/view/417. Acesso em: 13 oct. 2025.