STOKER, P. H.; STOKER, H. G. (Henk). Vrugbare wetenskappe. Tydskrif vir Christelike Wetenskap | Journal for Christian Scholarship, [S. l.], v. 49, n. 4, p. 47–67, 2013. Disponível em: https://pubs.ufs.ac.za/index.php/tcw/article/view/360. Acesso em: 17 oct. 2025.