DE SWARDT, D. H. White-crested Helmet-Shrike in the Vredefort area, Northern Free State. Biodiversity Observations, [S. l.], v. 7, p. 1–2, 2016. Disponível em: https://journals.uct.ac.za/index.php/BO/article/view/296. Acesso em: 7 jul. 2022.