In 1976 Johnathan Katz published this book about "lesbians and gay men" and placed Dr. Hart (incorrectly) in the category of lesbians. However, despite his improper classification, Katz did bring more attention to this important person in transgender history. Dr. Hart shows us that transgender people have always been around, and we must thank him for giving us another example.
In the chapter titled Dr. J. Allen Gilbert; "Homosexuality and Its Treatment" (pages 258-279), Dr. Katz first introduces Dr. Gilbert and his treatment of Dr. Hart. He then includes the full article "Homosexuality and Its Treatment" by Dr. Gilbert, and proceeds to give his argument for placing Hart in the box of "lesbian." While we can forgive some of this on the times, this kept Dr. Hart in the lesbian category for decades while being referred to as Lucille before he was correctly renamed to Alan and he/him pronouns were used.
As I have never met Dr. Katz, I cannot state if he would still place Dr. Hart in the lesbian box. I can say that his work with LGBT history is very important to my research and the research of other queer historians. I can forgive him this mistake, as his other work has added volumes to the library of work.
If you are going to purchase, try to find it at a local bookshop, rather than a large corporation. Abebooks can connect you with a local bookseller to purchase it from. If you prefer libraries, you can find what libraries around you have it at World Cat.