William Cowper, James Thomson (1832). “The Works of Cowper and Thompson: Including Many Letters and Poems Never Before Published in this Country. With a New and Interesting Memoir of the Life of Thomson”, p.162
Marcus Tullius Cicero (1855). “Cicero's Three books of offices, or moral duties: also his Cato Major, an essay on old age; Lælius, an essay on friendship; Paradoxes; Scipio's dream; and Letter to Quintus on the duties of a magistrate”, p.239
"Experiments With Alternate Currents Of High Potential And High Frequency". Nikola Tesla's Address to the Institution of Electrical Engineers, February 1892.
Oswald Chambers (2015). “Our Brilliant Heritage / If You Will Be Perfect / Disciples Indeed: The Inheritance of God's Transforming Mind & Heart”, p.228, Discovery House
Marcus Tullius Cicero (1855). “Cicero's Three books of offices, or moral duties: also his Cato Major, an essay on old age; Lælius, an essay on friendship; Paradoxes; Scipio's dream; and Letter to Quintus on the duties of a magistrate”, p.73