(en) Ron Legro et Avi Lank, The Man Who Painted the Universe, The Story of a Planetarium in the Heart of the North Woods, Madison (Wisconsin), Wisconsin Historical Society Press, , 118 p. (ISBN978-0-87020-711-2), « Of Hodags and Poniatowski », p. 36–37 [lire en ligne].
(en) Frank E. Barmore, « The Earth Isn’t Flat. And It Isn’t Round Either! : Some Significant and Little Known Effects of the Earth’s Ellipsoidal Shape », The Wisconsin Geographer, vol. 8, , p. 1–9 (lire en ligne), § « The Geographic Center », p. 4–6.