“Steel Industry Executive Summary: July 2012”, U. S. Department of Commerce, International Trade Administration, http://hq-web03.ita.doc.gov/License/Surge.nsf/webfles/SteelMillDevelopments/$fle/exec%20summ.pdf?openelement; Mark Piepkorn, “Lumber by the Numbers”, Continuing Education Center, http://continuingeducation.construction.com/article.php?L=5&C=645&P=1, originally published in GreenSource, January/February 2010 issue.
