Rademaker, C. “H.J.M. Nellen, C.M. Ridderikhoff, Briefwisseling Van Hugo Grotius, XV, Januari-September 1644”. BMGN - Low Countries Historical Review, vol. 114, no. 1, Jan. 1999, pp. 88-90, doi:10.18352/bmgn-lchr.4895.