1. Superstring Theory, vols. 1, 2;Green,1987
2. String Theory, vol. 1: An Introduction to the Bosonic String;Polchinski,1998
3. String Theory, vol. 2: Superstring Theory and Beyond;Polchinski,1998
4. Quantum Gravity;Rovelli,2004
5. Modern Canonical Quantum General Relativity;Thiemann,2007