“J.E. Burger, Linkse Frontvorming. Samenwerking Van Revolutionaire Socialisten 1914-1918”. BMGN - Low Countries Historical Review 100, no. 3 (January 1, 1985): 491–492. Accessed December 22, 2024. https://ojstest.minions.amsterdam/article/view/URN%3ANBN%3ANL%3AUI%3A10-1-102868.