Retrieved 2 April 2020. ↑ Graham Jenkin, Conquest of the Ngarrindjeri (1979), pp. 234-236, ISBN 0-7270-1112-X ↑ Harry E. Perrigo Archived 2007-10-08 at the Wayback Machine, a vertical file at the Kansas City Public Library in Kansas City, Missouri, described as follows: "Photos, illustrations, and information on Harry Perrigo, a local inventor of a "free energy" device in the 1910s-1920s turning out to be a hoax. Energy source of "invention" supposedly "from thin air" or from "ether waves" but in actually from a hidden battery." ↑ filed December 31, 1925; Serial Number 78,719 ↑ Citations originally at www.kclibrary.org resources Subject area ID 77176 ↑ Phillip Rowland. "The undying lure of perpetual motion".