The claims of channelers Jane Roberts (Seth Material), Helen Schucman ("A Course in Miracles"), J. Z. Knight (Ramtha), Neale Donald Walsch ("Conversations with God") (note that Walsch denies being a "channeler" and his books make it obvious that he is not one, though the text emerged through a dialogue with a deeper part of himself in a process comparable to automatic writing) contributed to the movement's growth. The first significant exponent of the New Age movement in the U.S. has been cited as Ram Dass. Core works in the propagating New Age ideas included Jane Roberts's Seth series, published from 1972 onward, Helen Schucman's 1975 publication "A Course in Miracles", and James Redfield's 1993 work "The Celestine Prophecy". A variety of these books were best sellers, with the Seth book series for instance selling over a million copies. Supplementing these books were videos, audiotapes, compact discs and websites. The development of the internet in particular further popularized New Age ideas and made them more widely accessible.