“A large mound in Sheboygan county yielded a large skeleton.”
Fifth Annual Report of the Bureau of Ethnology of the Smithsonian Institution 1883 – 1884. (pub. 1887)
(Path of Souls, 2014), Greg Little and Andrew Collins.
I personally have a few of these Smithsonian Annuals, but not this particular one. I am going to try to increase my library as these have such good references to giants, and are considered peer review by academia.