Sahlfeld , Wolfgang. “Méthode Intuitive: Interregional and International Circulation of a Pedagogical Idea (end of 19th Century)”. Rivista di Storia dell’Educazione 5, no. 2 (November 13, 2018): 59-72. Accessed October 21, 2021. https://rivistadistoriadelleducazione.it/index.php/rse/article/view/7621.