The latest is by the Tony Awards-winning Broadway star Tommy Tune. True to his creative nature, Tommy gave a endorsement for the book in the form of a poem.

My Experience with Brain Wave Vibration (a poem!)
To be guided to your own perfect rhythm,
to be coaxed yet never forced,
to be encouraged to find the unique vibration within,
and thus to live with it to its fullest
and highest degree.
This is the path as I perceive it. To each his own.