Blum, Alexander S. and Rickles, Dean (2018). Arthur Stanley Eddington (1918): Gravitation and the Principle of Relativity II. In: Quantum Gravity in the First Half of the Twentieth Century: A Sourcebook. Berlin: Max-Planck-Gesellschaft zur Förderung der Wissenschaften.
Arthur Stanley Eddington (1918). Gravitation and the Principle of Relativity II. Nature 101(2524): 34–36.