1. McClelland, S. (ed.) Future Histories. Pub. Nokia and Horizon House (June 1997)
2. Bell, A.G.: An Improvement in Telegraphy; US Pat. No. 174,465 (filed February 14 1876), (granted March 7, 1876)
3. Edison T.: Improvement in Phonograph or Speaking Machines; US Pat. No. 200,521 (filed December 24, 1877), (granted February 19, 1878)
4. Scientific American, pp. 384–385 (December 22, 1877)
5. Nipkow, P. G.: An electric telescope for the electric reproduction of illuminating objects. German Pat. No. 30105, (granted January 15, 1885) (retroactive January 6, 1884).