Quantum field theory on curved spacetime

Birrell and Davies, Quantum fields in curved space

Parker and Toms, Quantum field theory in curved spacetime

Fulling, Aspects of quantum field theory in curved spacetime

Wald, Quantum field theory in curved spacetime and black hole thermodynamics

Bar and Fredenhagen, Quantum field theory on curved spacetimes

Hack, Cosmological applications of algebraic quantum field theory in curved spacetimes

Hollands, Renormalized Quantum Yang-Mills Fields in Curved Spacetime, Rev.Math.Phys 20 (2008) 1033-1172.

Relevant mathematics: Everything needed for quantum field theory and general relativity.