Frithjof Schuon dans (en) Thomas Yellowtail et Michael Oren Fitzgerald, Yellowtail, Crow Medicine Man and Sun Dance Chief : An Autobiography, University of Oklahoma Press, , 270 p. (ISBN978-0-8061-2602-9, lire en ligne), p. 211.« Objections are sometimes raised to name the "Great Spirit" as a translation of the Sioux word Wakan-Tanka and of similar terms in other Indian languages; but though Wakan-Tanka (and the words which correspond to it) can also be translated by "Great Mystery" or "Great Mysterious Power" (or even "Great Medecine"), and though "Great Spirit", is no doubt no absolute adequate, it nonetheless serves quite well enough and in any case conveys the meaning in question better than any other words. ».
(en) John Gneisenau Neihardt, The Sixth Grandfather : Black Elk's Teachings Given to John G. Neihardt, U of Nebraska Press, , 452 p. (ISBN978-0-8032-6564-6, lire en ligne), p. 81.
(en) Raymond J. DeMallie et Douglas R. Parks, Sioux Indian Religion : Tradition and Innovation, University of Oklahoma Press, , 243 p. (ISBN978-0-8061-2166-6, lire en ligne), p. 28.