Map of the lower part of the Rock Island chain of rapids.
MLA
Map of the Lower Part of the Rock Island Chain of Rapids. E.H. Tracy, 0AD. https://collections.library.yale.edu/catalog/15830278.
APA, 6th edition
Map of the lower part of the Rock Island chain of rapids. (0 C.E.). [Maps]. E.H. Tracy, https://collections.library.yale.edu/catalog/15830278.