This is probably the best website with hundreds of links to research published around the world. It includes research for both standard HBOT and mild HBOT.
Another really useful site. You'll find more links to research, Youtube clips, and Dr Jason Sonners giving great explanations of how Hyperbaric Oxgen Therapy works and the benefits.
This is the International Hyperbarics Association, with plenty of information on anything and everything you need to know about Hyperbaric Oxygen Therapy.
Dr Masha podcasts are interesting to listen to, and very useful to help you understand more about HBOT. Hear real-life stories and interviews with doctors, specialists and practitioners.