Chuck Spezzano demonstrates how his attendance as a student in Oneness University influenced his thinking. According to this work's table of contents on Google Books, he talks about Hoʻoponopono elsewhere in the monograph. The book is entitled Wenn es fesselt, ist es keine Freiheit (2010)
https://books.google.com/books?id=4gy6aG9zovoC&printsec=frontcover&dq=Wenn+es+fesselt,+ist+es+keine+Freiheit&hl=en&sa=X&ved=0ahUKEwih4a3KgLHJAhUBEmMKHSztA44Q6AEIHzAA#v=onepage&q=Wenn%20es%20fesselt%2C%20ist%20es%20keine%20Freiheit&f=false