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"The Greenwich Hospital Smelt Mill at Langley, Northumberland 1768–1780" by F. J. Monkhouse, Transactions of the Institution of Mining and Metallurgy vol. 49, 1940. It is a Scheduled Ancient MonumentArchivado el 5 de diciembre de 2014 en Wayback Machine..
nachi.org
Nick Gromicko; Kenton Shepard. «the History of Concrete». The International Association of Certified Home Inspectors (InterNACHI). Consultado el 8 de enero de 2013.
"The Greenwich Hospital Smelt Mill at Langley, Northumberland 1768–1780" by F. J. Monkhouse, Transactions of the Institution of Mining and Metallurgy vol. 49, 1940. It is a Scheduled Ancient MonumentArchivado el 5 de diciembre de 2014 en Wayback Machine..