Veen, T. (1979) “B. de Spinoza, F. Akkerman, H.G. Hubbeling, A.G. Westerbrink, Briefwisseling, Akkerman, F., Hubbeling, H. G., Westerbrink, A. G., ed”., BMGN - Low Countries Historical Review, 94(2), pp. 300–302. doi:10.18352/bmgn-lchr.2100.