Frank-Walter Steinmeier, Federal President. «Address on the Opening Alexander Von Humboldt Season in Quito, Ecuador, on 13 February 2019 (With an Introduction by Ottmar Ette)». HiN – Alejandro de Humboldt en la Red. Revista internacional de estudios humboldtianos 20, no. 38 (agosto 6, 2019): 23–30. Accedido mayo 12, 2026. https://www.hin-online.de/index.php/hin/article/view/283.