If you’re going to attempt to provide a History of BDSM literature, you’d best begin by defining your terms.
There are a number of definitions available, but I think they are mostly flawed by the assumptions the writer has made before trying to say clearly what they mean.
Definitions by older psychological writers and practitioners, not to mention pseudoscientists like psychoanalysts, tend to build in the idea that bdsm is pathological. On the other hand, some more recent writers have assumed that bdsm is necessarily Safe, Sane and Consensual, so that activities that don’t fit into that ethical frame can simply be excluded and discounted.
This is my definition, and I think it’s the most accurate, with the fewest unstated assumptions, on the intellectual market. So it’s the definition I’m using when I discuss writing that expresses bdsm desires.