Witten, Edward (Spring 2011), "Knots and Quantum Theory"(PDF), The Institute Letter, archived from the original(PDF) on 27 September 2011, retrieved 17 August 2011
Witten, Edward (Spring 2011), "Knots and Quantum Theory"(PDF), The Institute Letter, archived from the original(PDF) on 27 September 2011, retrieved 17 August 2011