N. Björkenstam, "The Blast Furnace in Europe during the Medieval Times: part of a new system for producing wrought iron" in G. Magnusson (ed.), The importance of Ironmaking: Technical Innovation and Social Change, 143–53: papers presented at the Norberg conference 1995 I, Jernkontoret, Stockholm 1995.
N. S. B. Gras, The early English Customs System, 379. Harvard University Press, Cambridge, Mass. 1918. /wiki/N._S._B._Gras
Björkenstam, 150.
H. R. Schubert, History of the British iron and steel industry ... to 1775, 300–1. Routledge, London 1957.
S-E Åström, "From Cloth to Iron: the Anglo-Baltic trade in the late seventeenth century: I The growth, structure, and organisation of the trade", 33. Societas Scientarum Fennica: Commentationes Humanarum Littarum 33(1), Helsingfors 1963.
M. Kempa and Ü. Yalçin, "Medieval Iron Smelting in southern Germany: early evidence of pig iron" in G. Magnusson, The importance of Ironmaking I, 154–65; and other papers in the same volume.
M. B. Donald, Elizabethan Monopolies: the history of the Company of Mineral and Battery Works 1568-1604. Oliver & Boyd, Edinburgh 1961.
Schubert, 297–302.