[138] Herman Gerard Theodoor Frencken, “T bouck van wondre, 1513” (Leiden University, 1934), 75; Pastoureau speculates about an improved black dye method and mentions the use of (imported) tannin-rich dyestuff, Michel Pastoureau, Black: The History of a Color, English language ed. (Princeton, N.J: Princeton University Press, 2009), 92.