Kümmel. Proceedings of the American Association for the Advancement of Science, XLVI. 1897.
Mercer. Proceedings of the American Association for the Advancement of Science, XLVI. 1897.
Publications of the University of Pennsylvania, VI. 1897.
Putnam. Proceedings of the American Association for the Advancement of Science, VI. 1897.
Salisbury. Proceedings of the American Association for the Advancement of Science, VI. 1897.
Science, December 31, 1897.
Wilson. Report of the United States National Museum, 1897, 1.
Auringer. American Archæologist for February, 1898.
Thomas. American Archæology. 1898.
Blake. Journal of Geology, VII, 7. 1899.