Zach, Richard (1999). «Completeness before Post: Bernays, Hilbert, and the development of propositional logic». Bulletin of Symbolic Logic5: 331-366. JSTOR421184. doi:10.2307/421184.
Zach, Richard (1999). «Completeness before Post: Bernays, Hilbert, and the development of propositional logic». Bulletin of Symbolic Logic5: 331-366. JSTOR421184. doi:10.2307/421184.