Found most of them free, searching for them on the Internet Archives website. Here's the ones I've read:
The Invisible Rainbow - Arthur Firstenberg
The Contagion Myth - Thomas S. Cowan, Sally Fallon Morell
Béchamp or Pasteur? - Ethel Douglas Hume
Pasteur: Plagiarist, Impostor - R.B. Pearson
Also, I would follow Dr. Tom Cowan on SoMe/Youtube to get a broader updated view on the subject.
