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.