"Loops, Knots, Gauge Theories and Quantum Gravity" by Gambini and Pullin presents a unified, non-perturbative framework for quantum gravity using holonomies and loop representations. The work applies gauge theory techniques, specifically knot invariants and Ashtekar variables, to define physical states in a discrete, "pixelated" spacetime. The full text is available at Cambridge Core . Loops, Knots, Gauge Theories and Quantum Gravity