Frijhoff, W.Th.M. 1997. “J. Koopmans, Rhetoric - Rhétoriqueurs - Rederijkers. Proceedings of the Colloquium, Amsterdam, 10-13 November 1993”. BMGN - Low Countries Historical Review 112 (2): 265-66. https://doi.org/10.18352/bmgn-lchr.4471.