ENGELBRECHT, D.; GROSEL, J.; ENGELBRECHT, D. Nectar-feeding by southern African birds, with special reference to the Mountain Aloe Aloe marlothii. Biodiversity Observations, [S. l.], p. 49–74, 2014. Disponível em: https://journals.uct.ac.za/index.php/BO/article/view/217. Acesso em: 4 jul. 2022.