1. Canonical Quantum Gravity: from Classical to Quantum;Isham,1994
2. Integrable Systems, Quantum Groups, and Quantum Field Theories;Isham,1993
3. Non-Perturbative Canonical Quantum Gravity;Ashtekar,1991
4. C.J. Isham, Structural Issues in Quantum Gravity, gr-qc 9510063.
5. Relativity, Groups and Topology;Wheeler,1964