London: Routledge, 1931. hardcover. Translated for the first time into English with an Intorduction by Irvine Gray. Frontis., illustrated. x + 339pp., 8vo, cloth, d.w.; dust wrapper price clipped, lightly rubbed. London: George Routledge & Sons, Ltd., 1931. A very good copy in a very good dust wrapper. very good / very good.