[65] Judith H. Hofenk de, The Colourful Past: Origins, Chemistry and Identification of Natural Dyestuffs (London: Archetype Publ, 2004), 294-297; Natalia Ortega Saez, “Black Dyed Wool in North Western Europe, 1680-1850: The Relationship between Historical Recipes and the Current State of Preservation” (Doctoral thesis, University of Antwerp, Faculty of Design Sciences, 2018), 72-73; and see the essay in this collection by Ortega Saez and Cattersel on the various historical black dye technologies in this book;