Jules Romains

Eyeless Sight: A Study of Extra-Retinal Visoin and the Paroptic Sense

G. P. Putnam's Sons, London 1924.

Margery genuine says Conan Doyle; he scores Houdini

Boston Herald, 26 gennaio 1925.

G.B. Seybold

They Can See with Their Skin

Popular Science Monthly, dicembre 1925, p. 21.

Gwendolyn Kelley Hack

Modern Psychic Mysteries at Millesimo Castle

Rider, London 1929.

Gwendolyn Kelley Hack

The Direct Voice in Italy (1 of 2)

Psychic Science, N. 4, Vol. 7, gennaio 1929, pp. 272-330.

Gwendolyn Kelley Hack

The Direct Voice in Italy (2 of 2)

Psychic Science, N. 1, Vol. 8, aprile 1929, pp. 9-26.

Theodore Besterman

Review of Modern Psychic Mysteries book

Journal of the Society for Psychical Research, N. 461, Vol. 26, London gennaio 1930, pp. 10-14.

Montague Summers

The Physical Phenomena of Mysticism

Barnes & Noble, New York 1950.