"JVA - Computing History". John Vincent Atanasoff and the Birth Of Electronic Digital Computing. JVA Initiative Committee and Iowa State University. 2011.
"ABC Reconstruction, 1994-1997" (Press release). Iowa State University and John Vincent Atanasoff Initiative Committee. 2011.
John Gustafson.
"Reconstruction of the Atanasoff-Berry Computer".
Quote: "the total vacuum tube count was very low: about 300 for the entire machine. Much of this economy is the result of operating on only one bit of each number at a time, keeping the carry/borrow bit in a capacitor for use in the next cycle."
John Presper Eckert Jr. and John W. Mauchly, Electronic Numerical Integrator and Computer, U.S. patent 3,120,606, filed 26 June 1947, issued 4 February 1964, and invalidated 19 October 1973 after court ruling on Honeywell v. Sperry Rand.
stanford.edu
plato.stanford.edu
Copeland, B. Jack (6 April 2018). Zalta, Edward N. (ed.). The Stanford Encyclopedia of Philosophy. Metaphysics Research Lab, Stanford University. Retrieved 6 April 2018 – via Stanford Encyclopedia of Philosophy.