Bolerium Books: https://www.bolerium.com 

Bound Together Anarchist Bookstore: https://boundtogether.org 

Edward Carpenter Circle: https://www.edwardcarpentercircle.com

Gerard Koskovich Queer Antiquarian Books: https://www.abaa.org/bookstores/gerard-koskovich-queer-antiquarian-books

GLBT Historical Society: https://www.glbthistory.org

LGBTQ America: A Theme Study of Lesbian, Gay, Bisexual, Transgender, and Queer History (mentioned by Gerard Koskovich as the 2016 National Park Service report): https://npshistory.com/publications/nhl/theme-studies/lgbtq-america.pdf

Louise Lawrence Transgender Archive: https://lltransarchive.org 

Vintage Cross-Dressing Postcards at Cornell’s Human Sexuality Collection: https://digital.library.cornell.edu/collections/impersonator-postcards   

Wellcome Library: https://bit.ly/Wellcome-Library_Koskovich