Complex sentence: It was originally published in 1987 by the publishing division of the Hazelden Foundation, and became a phenomenon of the self-help movement, going on to sell over eight million copies, six million copies of them in the United States.
Split into simpler sentences: It was originally published in 1987 by the publishing division of the Hazelden Foundation. The book became a phenomenon of the self-help movement, going on to sell over eight million copies, six million copies of them in the United States.