1. On the soul by Aristotle, written 350 BCE, translated by J.A. Smith, available online at http://classics.mit.edu//Aristotle/soul.html.
2. Lives of the eminent philosophers/Book I - Thales by Diogenes Laertius, translated by R.D. Hicks, available online at https://en.wikisource.org/wiki/Lives_of_the_Eminent_Philosophers/Book_I.
3. The Age of electricity: From amber-soul to telephone;Benjamin,1889
4. The Origin of William Gilbert's scientific method;Zilsel;J. Hist. Ideas,1941
5. The early history of the electrodeposition and separation of particles;Robinson;J. Electrochem. Soc.,1968