UNITED STATES v. PENN-OLIN CHEMICAL CO.. The Oyez Project at IIT Chicago-Kent College of Law. 17 May 2012. <http://www.oyez.org/cases/1960-1969/1967/1967_26>.
UNITED STATES v. PENN-OLIN CHEMICAL CO., The Oyez Project at IIT Chicago-Kent College of Law, http://www.oyez.org/cases/1960-1969/1967/1967_26 (last visited May 17, 2012).
"UNITED STATES v. PENN-OLIN CHEMICAL CO.," The Oyez Project at IIT Chicago-Kent College of Law, accessed May 17, 2012, http://www.oyez.org/cases/1960-1969/1967/1967_26.