Stein, Stephen K. 2021. Sadomasochism and the BDSM community in the United States: kinky people unite. New York : Routledge, Taylor & Francis Group
Stein’s first chapter, which attempts to describe the proto-BDSM culture of the early and mid twentieth century, is a necessarily scattershot collection of data points. Research any historical field long enough and the gaps in the record become clear. We know so little about the sadomasochistic subculture prior to the 1970s. There’s some data about the gay subset, precious little about straights, and practically nothing about lesbians. Stein had access to the Kinsey Institute, the Carter Johnson Leather Library, the NLA Archives and more, and even then he couldn’t shed any new light on American BDSM before 1970.
Stein treats the BDSM culture as a whole, whereas I think it is more accurate to describe it as three parallel but separate streams (gay, lesbian, and straight), each with their own economy, and culture, that occasionally influence each other.