Peter Boag wrote an article for Western Historical Quarterly call “Go West Young Man, Go East Young Woman: Searching for the Trans in Western Gender History.” where he writes about Dr. Hart as well as other transgender people in late 19th and early 20th century America, including Elsa Jane Guerin who became Mountain Charlie and Elvira Virginia Mugarrieta who became Jack Garland. You can find a copy of it on JStor where you can get 100 articles a month for free.
Boag, Peter. “Go West Young Man, Go East Young Woman: Searching for the Trans in Western Gender History.” The Western Historical Quarterly, vol. 36, no. 4, 2005, pp. 477–97. JSTOR, https://doi.org/10.2307/25443237. Accessed 10 Mar. 2023.