Pennsylvania؛ Pennsylvania. Dept. of Property and Supplies؛ Pennsylvania. Bureau of Publications (1971). The Pennsylvania Manual. Department of Property and Supplies for the Commonwealth of Pennsylvania. ج. 100. مؤرشف من الأصل في 2016-04-26. اطلع عليه بتاريخ 2015-02-27.
Pennsylvania؛ Pennsylvania. Dept. of Property and Supplies؛ Pennsylvania. Bureau of Publications (1971). The Pennsylvania Manual. Department of Property and Supplies for the Commonwealth of Pennsylvania. ج. 100. مؤرشف من الأصل في 2016-04-26. اطلع عليه بتاريخ 2015-02-27.