There is a great deal of research available to educate and immerse yourself into learning about neurofeedback. On each of the pages of conditions I highlight a few major studies. If you’d like to go more in-depth I recommend the following resources:
International Society for Neuroregulation and Research (ISNR) has a fairly comprehensive bibliography.
EEG Info has a good list of major studies on their Research page.
National Library of Medicine Database – Pubmed