books.google.com - Mathematical Logic is a collection of the works of one of the leading figures in 20th-century science. This collection of A.M. Turing's works is intended to include all his mature scientific writing, including a substantial quantity of unpublished material. His work in pure mathematics and mathematical...https://books.google.com/books/about/Mathematical_Logic.html?id=5G4Eya27gCgC&q=squares&utm_source=gb-gplus-shareMathematical Logic