On the subplanes of the Hughes planes of odd square prime order. Annual of Sofia University St. Kliment Ohridski. Faculty of Mathematics and Informatics, [S. l.], v. 92, p. 65–72, 2000. Disponível em: https://annual.uni-sofia.bg/index.php/fmi/article/view/255. Acesso em: 15 dec. 2025.