" ISBN 978-3-84823-445-5* Patrick Grim, "Philosophy of science and the occult" ISBN 978-0-7914-0204-7*Lawrence LeShan, "The Medium, the Mystic, and the Physicist: Toward a General Theory of the Paranormal", 2003, Helios Press, ISBN 978-1-58115-273-9*Jack Sarfatti, 1975, "Space-Time and Beyond", with Fred Alan Wolf and Bob Toben, E. P. Dutton.
" ISBN 978-3-8482-3445-5* Patrick Grim, "Philosophy of science and the occult" ISBN 978-0-7914-0204-7* Lawrence LeShan, "The Medium, the Mystic, and the Physicist: Toward a General Theory of the Paranormal", 2003, Helios Press, ISBN 978-1-58115-273-9* Jack Sarfatti, 1975, "Space-Time and Beyond", with Fred Alan Wolf and Bob Toben, E. P. Dutton.