Trying to do some research on the effects of biofeedback

I'm doing some research on the effects of using biofeedback.  I'm
trying to look for research, articles, papers, etc. comparing the
results of biofeedback training and meditation and hypnagogic states.
Also looking for research, articles about what people think alpha and
theta waves represent and how asymmetry or waves being more prevalent
in one hemisphere than another or one part of the brain versus another
might affect that.  For instance, some research connects presence of
theta waves with activities such as storing memories and daydreaming.

If anyone has any pointers to information on these subjects, would
greatly appreciate hearing about it.

Thank you very much.

Sincerely,
Laura