Chicago: John Jacob Astor, "Preface," A Journey in Other Worlds in A Journey in Other Worlds (New York: The Century Co., 1918), Original Sources, accessed April 18, 2024, http://www.originalsources.com/Document.aspx?DocID=4YX66FDQ4BHQ8PG.
MLA: Astor, John Jacob. "Preface." A Journey in Other Worlds, in A Journey in Other Worlds, New York, The Century Co., 1918, Original Sources. 18 Apr. 2024. http://www.originalsources.com/Document.aspx?DocID=4YX66FDQ4BHQ8PG.
Harvard: Astor, JJ, 'Preface' in A Journey in Other Worlds. cited in 1918, A Journey in Other Worlds, The Century Co., New York. Original Sources, retrieved 18 April 2024, from http://www.originalsources.com/Document.aspx?DocID=4YX66FDQ4BHQ8PG.