UNITED STATES v. PENN-OLIN CO.. The Oyez Project at IIT Chicago-Kent College of Law. 12 February 2012. <http://www.oyez.org/cases/1960-1969/1963/1963_503>.
UNITED STATES v. PENN-OLIN CO., The Oyez Project at IIT Chicago-Kent College of Law, http://www.oyez.org/cases/1960-1969/1963/1963_503 (last visited February 12, 2012).
"UNITED STATES v. PENN-OLIN CO.," The Oyez Project at IIT Chicago-Kent College of Law, accessed February 12, 2012, http://www.oyez.org/cases/1960-1969/1963/1963_503.