Pollmann, T. “C. Blotkamp, De Vervolgjaren Van De Stijl, 1922-1932”. BMGN - Low Countries Historical Review 113, no. 4 (January 1, 1998): 598–600. Accessed May 4, 2024. https://bmgn-lchr.nl/article/view/URN%3ANBN%3ANL%3AUI%3A10-1-105588.