JANSSEN, J. R. Pütz, Duel in de wolken. De luchtoorlog in de gevarendriehoek Roermond–Luik–Aken. BMGN - Low Countries Historical Review, [S. l.], v. 111, n. 2, p. 284–285, 1996. DOI: 10.18352/bmgn-lchr.4271. Disponível em: https://bmgn-lchr.nl/article/view/URN%3ANBN%3ANL%3AUI%3A10-1-104907. Acesso em: 29 mar. 2024.