Frijhoff, W.Th.M. “J. Koopmans, Rhetoric - Rhétoriqueurs - Rederijkers. Proceedings of the Colloquium, Amsterdam, 10-13 November 1993”. BMGN - Low Countries Historical Review, vol. 112, no. 2, Jan. 1997, pp. 265-6, https://doi.org/10.18352/bmgn-lchr.4471.