Freeman, R. A. (1936). The Penrose mystery. Blue Ribbon Books.
Chicagoスタイル(17版)引用形式Freeman, R. Austin. The Penrose Mystery. New York: Blue Ribbon Books, 1936.
MLA(8版)引用形式Freeman, R. Austin. The Penrose Mystery. Blue Ribbon Books, 1936.
警告: この引用は必ずしも正確ではありません.