Jonker, Joost. “Kenneth Bertrams, Nicolas Coupain, Ernst Homburg, Solvay: History of a Multinational Family Firm”. BMGN - Low Countries Historical Review 128, no. 4 (October 30, 2013): review 91. Accessed April 25, 2024. https://bmgn-lchr.nl/article/view/URN%3ANBN%3ANL%3AUI%3A10-1-110015.