The book is built on primary papers, oral histories, archives and the standard scholarly histories of each period. The principal sources for each chapter are listed here as the chapter is serialised.
Chapter One | The Countess and the Engine
- Babbage Passages from the Life of a Philosopher (1864)
- Buxton/Hyman Memoir (1988)
- Swade The Cogwheel Brain (2000)
- Toole Ada, the Enchantress of Numbers (1992)
- Wolfram "Untangling the Tale of Ada Lovelace" (2015)
Chapter Two | Boolean Dreams
- Boole An Investigation of the Laws of Thought (1854)
- Shannon "A Symbolic Analysis of Relay and Switching Circuits" (1937)
- Soni/Goodman A Mind at Play (2017)
- MacHale The Life and Work of George Boole (2014)
- Goldstine The Computer from Pascal to von Neumann (1972)
- Gardner The Mind's New Science (1985)
Chapter Three | The Imaginary Machine
- Turing "On Computable Numbers" (1936)
- Turing "Computing Machinery and Intelligence" (1950)
- Hodges Alan Turing: The Enigma (1983/2014)
- Copeland Turing: Pioneer of the Information Age (2012)
- Godel "On Formally Undecidable Propositions" (1931)
- Church "An Unsolvable Problem of Elementary Number Theory" (1936)
- Coghlan et al. "Percy Ludgate" (2021)
- IEEE Spectrum on Torres y Quevedo
- Zuse Internet Archive