Lewandowski, Jerzy Quantum Gravity & Unified Theories, AEI-Golm, MPI for Gravitational Physics, Max Planck Society;
quantum.pdf (Preprint), 384KB
Ashtekar, A., & Lewandowski, J. (1997). Quantum Theory of Geometry II: Volume operators. Advances in Theoretical and Mathematical Physics, 1(2), 388-429.