Frieswijk, Johan. “Bert Altena, Machinist En Wereldverbeteraar. Het Leven Van A.J. Lansen, 1847-1931”. TSEG - The Low Countries Journal of Social and Economic History 12, no. 3 (September 15, 2015): 116–118. Accessed April 11, 2026. https://testplatform.openjournals.nl/tseg/article/view/7348.