Feynman Quantum theory of gravitation
DeWitt Quantum theory of gravity 1 – canonical theory
DeWitt Quantum theory of gravity 2 – covariant theory
DeWitt Quantum theory of gravity 3 – applications of the covariant theory
Kibble’s treatment of gravity as gauged Lorentz symmetry
Utiyama Gravity as a gauge theory.
Weinberg – Infrared photons and gravitons 1965
‘t Hooft and Veltman’s classic on one loop gravity.