Alt, Heinrich. “Platonisme, Konseptualisme En Nomimalisme in Die Versamelingsteorie”. Tydskrif vir Christelike Wetenskap | Journal for Christian Scholarship 57, no. 3&4 (December 29, 2021): 31–52. Accessed October 5, 2025. https://pubs.ufs.ac.za/index.php/tcw/article/view/557.