1. Ember CR. Ethnology. 1978 17(4) 439–4482.
2. Capek Karel, Czech playwright, Rossums Universal Robots.
3. Steadman’s Medical Dictionary 27th Ed Lippincott, Williams, Wilkins Pub.
4. Heron 3rd Century Greece.
5. Quintus Septimus Tertullian (US), De Anima, Chap 6, Sec 3, C 155—220 AD, Michael Byron’s, The Puppet Theater in Antiquity.