I. Cornelissen, De GPOe op de Overtoom. Spionnen voor Moskou 1920-1940. BMGN - Low Countries Historical Review, [S. l.], v. 107, n. 2, p. 373–374, 1992. DOI: 10.18352/bmgn-lchr.3555. Disponível em: https://ojstest.minions.amsterdam/article/view/URN%3ANBN%3ANL%3AUI%3A10-1-104082.. Acesso em: 22 dec. 2024.