HÖGGEMEIER, Annette; JAGEL, Armin. Christrose – Helleborus niger. Der Palmengarten, [S. l.], v. 72, n. 2, p. 164–165, 2018. DOI: 10.21248/palmengarten.364. Disponível em: https://ojs.ub.uni-frankfurt.de/Palmengarten/index.php/Palmengarten/article/view/364. Acesso em: 19 mai. 2024.